Need to know where o2sensor plugs in - 1987 Chevrolet S-10 Pickup

Plugged catalytic converter , Do a exhaust back pressure test ! Pull the O2sensor install back pressure gauge .

Black/Dark green.

Sensor diagram for a 2000 toyota avalon and list of Pcodes

P0100 Mass or Volume Air Flow Circuit Malfunction
P0101 Mass or Volume Air Flow Circuit Range/Performance Problem
P0102 Mass or Volume Air Flow Circuit Low Input
P0103 Mass or Volume Air Flow Circuit High Input
P0104 Mass or Volume Air Flow Circuit Intermittent
P0105 Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
P0106 Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0107 Manifold Absolute Pressure/Barometric Pressure Circuit Low Input
P0108 Manifold Absolute Pressure/Barometric Pressure Circuit High Input
P0109 Manifold Absolute Pressure/Barometric Pressure Circuit Intermittent
P0110 Intake Air Temperature Circuit Malfunction
P0111 Intake Air Temperature Circuit Range/Performance Problem
P0112 Intake Air Temperature Circuit Low Input
P0113 Intake Air Temperature Circuit High Input
P0114 Intake Air Temperature Circuit Intermittent
P0115 Engine Coolant Temperature Circuit Malfunction
P0116 Engine Coolant Temperature Circuit Range/Performance Problem
P0117 Engine Coolant Temperature Circuit Low Input
P0118 Engine Coolant Temperature Circuit High Input
P0119 Engine Coolant Temperature Circuit Intermittent
P0120 Throttle/Pedal Position Sensor/Switch "A" Circuit Malfunction
P0121 Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance Problem
P0122 Throttle/Pedal Position Sensor/Switch "A" Circuit Low Input
P0123 Throttle/Pedal Position Sensor/Switch "A" Circuit High Input
P0124 Throttle/Pedal Position Sensor/Switch "A" Circuit Intermittent
P0125 Insufficient Coolant Temperature For Closed Loop Fuel Control
P0126 Insufficient Coolant Temperature For Stable Operation
P0130 O2Circuit Malfunction (Bank #1 Sensor #1)
P0131 O2Sensor Circuit Low Voltage (Bank #1 Sensor #1)
P0132 O2Sensor Circuit High Voltage (Bank #1 Sensor #1)
P0133 O2Sensor Circuit Slow Response (Bank #1 Sensor #1)
P0134 O2Sensor Circuit No Activity Detected (Bank #1 Sensor #1)
P0135 O2Sensor Heater Circuit Malfunction (Bank #1 Sensor #1)
P0136 O2Sensor Circuit Malfunction (Bank #1 Sensor #2)
P0137 O2Sensor Circuit Low Voltage (Bank #1 Sensor #2)
P0138 O2Sensor Circuit High Voltage (Bank #1 Sensor #2)
P0139 O2Sensor Circuit Slow Response (Bank #1 Sensor #2)
P0140 O2Sensor Circuit No Activity Detected (Bank #1 Sensor #2)
P0141 O2Sensor Heater Circuit Malfunction (Bank #1 Sensor #2)
P0142 O2Sensor Circuit Malfunction (Bank #1 Sensor #3)
P0143 O2Sensor Circuit Low Voltage (Bank #1 Sensor #3)
P0144 O2Sensor Circuit High Voltage (Bank #1 Sensor #3)
P0145 O2Sensor Circuit Slow Response (Bank #1 Sensor #3)
P0146 O2Sensor Circuit No Activity Detected (Bank #1 Sensor #3)
P0147 O2Sensor Heater Circuit Malfunction (Bank #1 Sensor #3)
P0150 O2Sensor Circuit Malfunction (Bank #2 Sensor #1)
P0151 O2Sensor Circuit Low Voltage (Bank #2 Sensor #1)
P0152 O2Sensor Circuit High Voltage (Bank #2 Sensor #1)
P0153 O2Sensor Circuit Slow Response (Bank #2 Sensor #1)
P0154 O2Sensor Circuit No Activity Detected (Bank #2 Sensor #1)
P0155 O2Sensor Heater Circuit Malfunction (Bank #2 Sensor #1)
P0156 O2Sensor Circuit Malfunction (Bank #2 Sensor #2)
P0157 O2Sensor Circuit Low Voltage (Bank #2 Sensor #2)
P0158 O2Sensor Circuit High Voltage (Bank #2 Sensor #2)
P0159 O2Sensor Circuit Slow Response (Bank #2 Sensor #2)
P0160 O2Sensor Circuit No Activity Detected (Bank #2 Sensor #2)
P0161 O2Sensor Heater Circuit Malfunction (Bank #2 Sensor #2)
P0162 O2Sensor Circuit Malfunction (Bank #2 Sensor #3)
P0163 O2Sensor Circuit Low Voltage (Bank #2 Sensor #3)
P0164 O2Sensor Circuit High Voltage (Bank #2 Sensor #3)
P0165 O2Sensor Circuit Slow Response (Bank #2 Sensor #3)
P0166 O2Sensor Circuit No Activity Detected (Bank #2 Sensor #3)
P0167 O2Sensor Heater Circuit Malfunction (Bank #2 Sensor #3)
P0170 Fuel Trim Malfunction (Bank #1)
P0171 System Too Lean (Bank #1)
P0172 System Too Rich (Bank #1)
P0173 Fuel Trim Malfunction (Bank #2)
P0174 System Too Lean (Bank #2)
P0175 System Too Rich (Bank #2)
P0176 Fuel Composition Sensor Circuit Malfunction
P0177 Fuel Composition Sensor Circuit Range/Performance
P0178 Fuel Composition Sensor Circuit Low Input
P0179 Fuel Composition Sensor Circuit High Input
P0180 Fuel Temperature Sensor "A" Circuit Malfunction
P0181 Fuel Temperature Sensor "A" Circuit Range/Performance
P0182 Fuel Temperature Sensor "A" Circuit Low Input
P0183 Fuel Temperature Sensor "A" Circuit High Input
P0184 Fuel Temperature Sensor "A" Circuit Intermittent
P0185 Fuel Temperature Sensor "B" Circuit Malfunction
P0186 Fuel Temperature Sensor "B" Circuit Range/Performance
P0187 Fuel Temperature Sensor "B" Circuit Low Input
P0188 Fuel Temperature Sensor "B" Circuit High Input
P0189 Fuel Temperature Sensor "B" Circuit Intermittent
P0190 Fuel Rail Pressure Sensor Circuit Malfunction
P0191 Fuel Rail Pressure Sensor Circuit Range/Performance
P0192 Fuel Rail Pressure Sensor Circuit Low Input
P0193 Fuel Rail Pressure Sensor Circuit High Input
P0194 Fuel Rail Pressure Sensor Circuit Intermittent
P0195 Engine Oil Temperature Sensor Malfunction
P0196 Engine Oil Temperature Sensor Range/Performance
P0197 Engine Oil Temperature Sensor Low
P0198 Engine Oil Temperature Sensor High
P0199 Engine Oil Temperature Sensor Intermittent
P0200 Injector Circuit Malfunction
P0201 Injector Circuit Malfunction - Cylinder #1
P0202 Injector Circuit Malfunction - Cylinder #2
P0203 Injector Circuit Malfunction - Cylinder #3
P0204 Injector Circuit Malfunction - Cylinder #4
P0205 Injector Circuit Malfunction - Cylinder #5
P0206 Injector Circuit Malfunction - Cylinder #6
P0207 Injector Circuit Malfunction - Cylinder #7
P0208 Injector Circuit Malfunction - Cylinder #8
P0209 Injector Circuit Malfunction - Cylinder #9
P0210 Injector Circuit Malfunction - Cylinder #10
P0211 Injector Circuit Malfunction - Cylinder #11
P0212 Injector Circuit Malfunction - Cylinder #12
P0213 Cold Start Injector #1 Malfunction
P0214 Cold Start Injector #2 Malfunction
P0215 Engine Shutoff Solenoid Malfunction
P0216 Injection Timing Control Circuit Malfunction
P0217 Engine Over Temperature Condition
P0218 Transmission Over Temperature Condition
P0219 Engine Over Speed Condition
P0220 Throttle/Pedal Position Sensor/Switch "B" Circuit Malfunction
P0221 Throttle/Pedal Position Sensor/Switch "B" Circuit Range/Performance Problem
P0222 Throttle/Pedal Position Sensor/Switch "B" Circuit Low Input
P0223 Throttle/Pedal Position Sensor/Switch "B" Circuit High Input
P0224 Throttle/Pedal Position Sensor/Switch "B" Circuit Intermittent
P0225 Throttle/Pedal Position Sensor/Switch "C" Circuit Malfunction
P0226 Throttle/Pedal Position Sensor/Switch "C" Circuit Range/Performance Problem
P0227 Throttle/Pedal Position Sensor/Switch "C" Circuit Low Input
P0228 Throttle/Pedal Position Sensor/Switch "C" Circuit High Input
P0229 Throttle/Pedal Position Sensor/Switch "C" Circuit Intermittent
P0230 Fuel Pump Primary Circuit Malfunction
P0231 Fuel Pump Secondary Circuit Low
P0232 Fuel Pump Secondary Circuit High
P0233 Fuel Pump Secondary Circuit Intermittent
P0234 Engine Over Boost Condition
P0261 Cylinder #1 Injector Circuit Low
P0262 Cylinder #1 Injector Circuit High
P0263 Cylinder #1 Contribution/Balance Fault
P0264 Cylinder #2 Injector Circuit Low
P0265 Cylinder #2 Injector Circuit High
P0266 Cylinder #2 Contribution/Balance Fault
P0267 Cylinder #3 Injector Circuit Low
P0268 Cylinder #3 Injector Circuit High
P0269 Cylinder #3 Contribution/Balance Fault
P0270 Cylinder #4 Injector Circuit Low
P0271 Cylinder #4 Injector Circuit High
P0272 Cylinder #4 Contribution/Balance Fault
P0273 Cylinder #5 Injector Circuit Low
P0274 Cylinder #5 Injector Circuit High
P0275 Cylinder #5 Contribution/Balance Fault
P0276 Cylinder #6 Injector Circuit Low
P0277 Cylinder #6 Injector Circuit High
P0278 Cylinder #6 Contribution/Balance Fault
P0279 Cylinder #7 Injector Circuit Low
P0280 Cylinder #7 Injector Circuit High
P0281 Cylinder #7 Contribution/Balance Fault
P0282 Cylinder #8 Injector Circuit Low
P0283 Cylinder #8 Injector Circuit High
P0284 Cylinder #8 Contribution/Balance Fault
P0285 Cylinder #9 Injector Circuit Low
P0286 Cylinder #9 Injector Circuit High
P0287 Cylinder #9 Contribution/Balance Fault
P0288 Cylinder #10 Injector Circuit Low
P0289 Cylinder #10 Injector Circuit High
P0290 Cylinder #10 Contribution/Balance Fault
P0291 Cylinder #11 Injector Circuit Low
P0292 Cylinder #11 Injector Circuit High
P0293 Cylinder #11 Contribution/Balance Fault
P0294 Cylinder #12 Injector Circuit Low
P0295 Cylinder #12 Injector Circuit High
P0296 Cylinder #12 Contribution/Balance Fault
P0300 Random/Multiple Cylinder Misfire Detected
P0301 Cylinder #1 - Misfire Detected
P0302 Cylinder #2 - Misfire Detected
P0303 Cylinder #3 - Misfire Detected
P0304 Cylinder #4 - Misfire Detected
P0305 Cylinder #5 - Misfire Detected
P0306 Cylinder #6 - Misfire Detected
P0307 Cylinder #7 - Misfire Detected
P0308 Cylinder #8 - Misfire Detected
P0320 Ignition/Distributor Engine Speed Input Circuit Malfunction
P0321 Ignition/Distributor Engine Speed Input Circuit Range/Performance
P0322 Ignition/Distributor Engine Speed Input Circuit No Signal
P0323 Ignition/Distributor Engine Speed Input Circuit Intermittent
P0325 Knock Sensor #1 - Circuit Malfunction (Bank #1 or Single Sensor)
P0326 nock Sensor #1 - Circuit Range/Performance (Bank #1 or Single Sensor)
P0327 Knock Sensor #1 - Circuit Low Input (Bank #1 or Single Sensor)
P0328 Knock Sensor #1 - Circuit High Input (Bank #1 or Single Sensor)
P0329 Knock Sensor #1 - Circuit Input Intermittent (Bank #1 or Single Sensor)
P0330 Knock Sensor #2 - Circuit Malfunction (Bank #2)
P0331 Knock Sensor #2 - Circuit Range/Performance (Bank #2)
P0332 Knock Sensor #2 - Circuit Low Input (Bank #2)
P0333 Knock Sensor #2 - Circuit High Input (Bank #2)
P0334 Knock Sensor #2 - Circuit Input Intermittent (Bank #2)
P0335 Crankshaft Position Sensor "A" Circuit Malfunction
P0336 Crankshaft Position Sensor "A" Circuit Range/Performance
P0337 Crankshaft Position Sensor "A" Circuit Low Input
P0338 Crankshaft Position Sensor "A" Circuit High Input
P0339 Crankshaft Position Sensor "A" Circuit Intermittent
P0340 Camshaft Position Sensor Circuit Malfunction
P0341 Camshaft Position Sensor Circuit Range/Performance
P0342 Camshaft Position Sensor Circuit Low Input
P0343 Camshaft Position Sensor Circuit High Input
P0344 Camshaft Position Sensor Circuit Intermittent
P0350 Ignition Coil Primary/Secondary Circuit Malfunction
P0351 Ignition Coil "A" Primary/Secondary Circuit Malfunction
P0352 Ignition Coil "B" Primary/Secondary Circuit Malfunction
P0353 Ignition Coil "C" Primary/Secondary Circuit Malfunction
P0354 Ignition Coil "D" Primary/Secondary Circuit Malfunction
P0355 Ignition Coil "E" Primary/Secondary Circuit Malfunction
P0356 Ignition Coil "F" Primary/Secondary Circuit Malfunction
P0357 Ignition Coil "G" Primary/Secondary Circuit Malfunction
P0358 Ignition Coil "H" Primary/Secondary Circuit Malfunction
P0359 Ignition Coil "I" Primary/Secondary Circuit Malfunction
P0360 Ignition Coil "J" Primary/Secondary Circuit Malfunction
P0361 Ignition Coil "K" Primary/Secondary Circuit Malfunction
P0362 Ignition Coil "L" Primary/Secondary Circuit Malfunction
P0370 Timing Reference High Resolution Signal "A" Malfunction
P0371 Timing Reference High Resolution Signal "A" Too Many Pulses
P0372 Timing Reference High Resolution Signal "A" Too Few Pulses
P0373 Timing Reference High Resolution Signal "A" Intermittent/Erratic Pulses
P0374 Timing Reference High Resolution Signal "A" No Pulses
P0375 Timing Reference High Resolution Signal "B" Malfunction
P0376 Timing Reference High Resolution Signal "B" Too Many Pulses
P0377 Timing Reference High Resolution Signal "B" Too Few Pulses
P0378 Timing Reference High Resolution Signal "B" Intermittent/Erratic Pulses
P0379 Timing Reference High Resolution Signal "B" No Pulses
P0380 Glow Plug/Heater Circuit "A" Malfunction
P0381 Glow Plug/Heater Indicator Circuit Malfunction
P0382 Glow Plug/Heater Circuit "B" Malfunction
P0385 Crankshaft Position Sensor "B" Circuit Malfunction
P0386 Crankshaft Position Sensor "B" Circuit Range/Performance
P0387 Crankshaft Position Sensor "B" Circuit Low Input
P0388 Crankshaft Position Sensor "B" Circuit High Input
P0389 Crankshaft Position Sensor "B" Circuit Intermittent
P0400 Exhaust Gas Recirculation Flow Malfunction
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0402 Exhaust Gas Recirculation Flow Excessive Detected
P0403 Exhaust Gas Recirculation Circuit Malfunction
P0404 Exhaust Gas Recirculation Circuit Range/Performance
P0405 Exhaust Gas Recirculation Sensor "A" Circuit Low
P0406 Exhaust Gas Recirculation Sensor "A" Circuit High
P0407 Exhaust Gas Recirculation Sensor "B" Circuit Low
P0408 Exhaust Gas Recirculation Sensor "B" Circuit High
P0410 Secondary Air Injection System Malfunction
P0411 Secondary Air Injection System Incorrect Flow Detected
P0412 Secondary Air Injection System Switching Valve "A" Circuit Malfunction
P0413 Secondary Air Injection System Switching Valve "A" Circuit Open
P0414 Secondary Air Injection System Switching Valve "A" Circuit Shorted
P0415 Secondary Air Injection System Switching Valve "B" Circuit Malfunction
P0416 Secondary Air Injection System Switching Valve "B" Circuit Open
P0417 Secondary Air Injection System Switching Valve "B" Circuit Shorted
P0418 Secondary Air Injection System Relay "A" Circuit Malfunction
P0419 Secondary Air Injection System Relay "B" Circuit Malfunction
P0420 Catalyst System Efficiency Below Threshold (Bank #1)
P0421 Warm Up Catalyst Efficiency Below Threshold (Bank #1)
P0422 Main Catalyst Efficiency Below Threshold (Bank #1)
P0423 Heated Catalyst Efficiency Below Threshold (Bank #1)
P0424 Heated Catalyst Temperature Below Threshold (Bank #1)
P0430 Catalyst System Efficiency Below Threshold (Bank #2)
P0431 Warm Up Catalyst Efficiency Below Threshold (Bank #2)
P0432 Main Catalyst Efficiency Below Threshold (Bank #2)
P0433 Heated Catalyst Efficiency Below Threshold (Bank #2)
P0434 Heated Catalyst Temperature Below Threshold (Bank #2)
P0440 Evaporative Emission Control System Malfunction
P0441 Evaporative Emission Control System Incorrect Purge Flow
P0442 Evaporative Emission Control System Leak Detected (Small Leak)
P0443 Evaporative Emission Control System Purge Control Valve Circuit Malfunction
P0444 Evaporative Emission Control System Purge Control Valve Circuit Open
P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted
P0446 Evaporative Emission Control System Vent Control Circuit Malfunction P0441 and/or P0446

check all vacuum lines for cracks or broken spots. if there is none you could need a new intake gasket.

so what are you working on make model and engine and year

o2sensors are located in the exhaust system.you have 4 o2sensors on your car.so you need to know which sensor your looking for.bank 1 sensor 1 is the first sensor in the exhaust pipe on the side cylinder 1 is on.bank 2 is on the side cylinder 2 is on.then you have a sensor before the catalytic convertor and one after the convertor.

LOCATIONS There are different locations in the exhaust system where O2sensors are positioned. The locations have been given numbers and will be used in the accompanying charts to identify the positions of O2sensors in most vehicles. Due to mid-year production changes or factory inconsistencies, all models may not be covered. If a vehicle being serviced is not covered in the charts, inspect the exhaust system (while cold!) in the general locations to find the applicable O2sensors. NOTE: If equipped with dual exhaust systems, there may be up to 4 or 5 O2sensors in the exhaust system. Be sure to locate all of them before commencing with any testing or service. Fig. 1: Location No. 1 - down pipe
Fig. 2: Location No. 1 - typical O2sensor located in the exhaust manifold
Fig. 3: Location No. 2 - left and right banks of a V-type engine
Fig. 4: Location No. 3 - exhaust collector (where more than 1 pipe joins together)
Fig. 5: Location No. 4 - outlet of the catalytic converter
Fig. 6: Location No. 5 - inlet and outlet of the catalytic converter

P0141 O2Sensor Heater Circuit Malfunction (Bank #1 Sensor #2)
P0300 Random/Multiple Cylinder Misfire Detected

The random multiple cylinder misfire can be caused by a bad O2 Sensor.

Try to change the O2 Sensor out, they can be tricky though, with the threads sometimes becoming gauled if removed when cold.

REMOVAL & INSTALLATION

1. Start the engine and allow it to reach normal operating temperature, then turn the ignition switch OFF.
2. Disconnect the negative battery cable.
3. Open the hood and locate the O2sensor connector. It may be necessary to raise and safely support the vehicle for access to the sensor and its connector. NOTE: On a few models, it may be necessary to remove the passenger seat and lift the carpeting in order to access the connector for a downstream O2sensor. Fig. 1: Since sensor locations vary between vehicles, the first step in removal is to locate the O2sensors (arrows) . . .
   Fig. 2: . . . and the sensor connector (2), which is usually near the O2sensor (1), but removed enough from the heat of the exhaust system
   Fig. 3: Disengage the sensor pigtail connector half from the vehicle harness connector half
   Fig. 4: For flange type sensors, loosen the hold-down fasteners . . .
   Fig. 5: . . . which happen to be nuts in this particular case - some models may use bolts rather than nuts
   Fig. 6: Then, pull the sensor out of the exhaust component
   Fig. 7: For screw-in type sensors (arrow) . . .
   Fig. 8: . . . either use a box end wrench to loosen the sensor or a socket designed expressly for this purpose . . .
   Fig. 9: . . . then remove the sensor from the exhaust component
   
   
4. Disengage the O2sensor pigtail connector from the vehicle harness connector. NOTE: There are generally 2 methods used to mount an O2sensor in the exhaust system. Either the O2sensor is threaded directly into the exhaust component (screw-in type) or the O2sensor is retained by a flange and 2 nuts or bolts (flange type). WARNING
   To prevent damaging a screw-in type O2sensor, if excessive force is needed to remove the sensor lubricate it with penetrating oil prior to removal. Also, be sure to protect the tip of the sensor; O2sensor tips are very sensitive and may be easily damaged if allowed to strike or come in contact with other objects.
   
5. Remove the sensor, as follows:
   • Screw-in type sensors: Since O2sensors are usually designed with a permanently-attached wiring pigtail, it may be necessary to use a socket or wrench that is designed specifically for this purpose. Before purchasing such a socket, be sure that you can't save some money by using a box end wrench for sensor removal.
   • Flange type sensors: Loosen the hold-down nuts or bolts and pull the sensor out of the exhaust component. Be sure to remove and discard the old sensor gasket, if equipped. You will need a new gasket for installation.
6. Perform a visual inspection of the sensor. Black sooty deposits may indicate a rich air/fuel mixture, brown deposits may indicate an oil consumption problem, and white gritty deposits may indicate an internal coolant leak. All of these conditions can destroy a new sensor if not corrected before installation. To install:
   
7. Install the sensor, as follows: NOTE: A special anti-seize compound is used on most screw-in type O2sensor threads, and is designed to ease O2sensor removal. New sensors usually have the compound already applied to the threads. However, if installing the old O2sensor or the new sensor did not come with compound, apply a thin coating of electrically conductive anti-seize compound to the sensor threads. WARNING
   Be sure to prevent any of the anti-seize compound from coming in contact with the O2sensor tip. Also, take precautions to protect the sensor tip from physical damage during installation.
   • Screw-in type sensors: Install the sensor in the mounting boss, then tighten it securely.
   • Flange type sensors: Position a new sensor gasket on the exhaust component and insert the sensor. Tighten the hold-down fasteners securely and evenly.
8. Reattach the sensor pigtail connector to the vehicle harness connector.
9. Lower the vehicle.
10. Connect the negative battery cable.
11. Start the engine and ensure no Diagnostic Trouble Codes (DTC's) are set.

REMOVAL & INSTALLATION Start the engine and allow it to reach normal operating temperature, then turn the ignition switch OFF. Disconnect the negative battery cable. Open the hood and locate the O2sensor connector. It may be necessary to raise and safely support the vehicle for access to the sensor and its connector. NOTE: On a few models, it may be necessary to remove the passenger seat and lift the carpeting in order to access the connector for a downstream O2sensor. Disengage the O2sensor pigtail connector from the vehicle harness connector. NOTE: There are generally 2 methods used to mount an O2sensor in the exhaust system. Either the O2sensor is threaded directly into the exhaust component (screw-in type) or the O2sensor is retained by a flange and 2 nuts or bolts (flange type). WARNING To prevent damaging a screw-in type O2sensor, if excessive force is needed to remove the sensor lubricate it with penetrating oil prior to removal. Also, be sure to protect the tip of the sensor; O2sensor tips are very sensitive and may be easily damaged if allowed to strike or come in contact with other objects. Remove the sensor, as follows: Screw-in type sensors: Since O2sensors are usually designed with a permanently-attached wiring pigtail, it may be necessary to use a socket or wrench that is designed specifically for this purpose. Before purchasing such a socket, be sure that you can't save some money by using a box end wrench for sensor removal. Flange type sensors: Loosen the hold-down nuts or bolts and pull the sensor out of the exhaust component. Be sure to remove and discard the old sensor gasket, if equipped. You will need a new gasket for installation. Perform a visual inspection of the sensor. Black sooty deposits may indicate a rich air/fuel mixture, brown deposits may indicate an oil consumption problem, and white gritty deposits may indicate an internal coolant leak. All of these conditions can destroy a new sensor if not corrected before installation. To install: Install the sensor, as follows: NOTE: A special anti-seize compound is used on most screw-in type O2sensor threads, and is designed to ease O2sensor removal. New sensors usually have the compound already applied to the threads. However, if installing the old O2sensor or the new sensor did not come with compound, apply a thin coating of electrically conductive anti-seize compound to the sensor threads. WARNING Be sure to prevent any of the anti-seize compound from coming in contact with the O2sensor tip. Also, take precautions to protect the sensor tip from physical damage during installation. Screw-in type sensors: Install the sensor in the mounting boss, then tighten it securely. Flange type sensors: Position a new sensor gasket on the exhaust component and insert the sensor. Tighten the hold-down fasteners securely and evenly. Reattach the sensor pigtail connector to the vehicle harness connector. Lower the vehicle. Connect the negative battery cable. Start the engine and ensure no Diagnostic Trouble Codes (DTC's) are set. Posting pictures next......

replace the valve seals for # 4 cylinder, they are allowing excessive oil to be pulled into the combustion chamber through the valve guides, these go because the #4 cylinder runs the hottest..