I have a 1999 S-10, 2.2L, 5-speed, extended cab. I have had both oxygen sensors and the catalytic converter replaced. The first oxygen sensor was replaced Mar 2005, the catalytic converter was replaced Oct 2005, and the second oxygen sensor was replaced Mar 2008. I have 166,000 miles on the truck. The Check Engine light keeps coming back on. I have taken it to my local mechanic to read the Fault Codes, and it stated (the last time) that the catalyst levels were out of tolerance). I asked him to reset the light, and I drove only about 140 miles before the Check Engine light came back on. I have noticed (on occasion) that the vehicle is hard to crank. Can you help me?
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DTC P0420 - Catalyst System Efficiency Below Threshold (Bank 1) The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.
You will likely not notice any drivability problems, although there may be symptoms.
A code P0420 may mean that one or more of the following has happened: Leaded fuel was used where unleaded was called for An oxygen sensor is not reading (functioning) properly The engine coolant temperature sensor is not working properly Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe ******** spark timing The oxygen sensors in front and behind the converter are reporting too similar of readings
Some suggested steps for troubleshooting a P0420 error code include: - Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required. - Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady). - Inspect the downstream heated oxygen sensor (HO2), replace if necessary - Replace the catalytic converter
One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.
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Hi Christian: The Check Engine or Service Engine Soon light or an icon resembling the engine is technically called a Malfunction Indicator Light or MIL.
It comes on when your vehicle's computer detects a fault that can
affect your vehicle's fuel economy and the exhaust emissions.
Here are the five most common reasons your "check engine" light might come on, and what you can expect to pay for the repair, including labor, according to CarMD:
1. Faulty oxygen sensor The sensor measures the amount of unburned oxygen in the exhaust and tells the car's computer how much fuel is in the tank. If a faulty one is not repaired, the car's gas mileage could drop, since the sensor is sending incorrect information to the car. It costs less than $200 to repair.
2. Loose or missing gas cap Technicians will often tighten the gas cap for free, or replace it for a few dollars. If it's not replaced, gas will evaporate from the car and decrease its gas mileage.
3. Broken catalytic converter This one isn't good news, since it can cost up to $2,000 to replace. The catalytic converter uses a catalyst -most often a precious metal such as platinum- to convert harmful gases left over from combustion to less harmful emissions. CarMD says catalytic converters generally won't fail unless a related part, such as a spark plug, malfunctions, so it's wise to keep up with the car's maintenance schedule.
4. Malfunctioning mass air flow sensor This sensor measures the amount of air supplied to the engine, which determines how much fuel should be delivered. When it malfunctions, it can result in a loss of power to the car, surges during acceleration and a decrease in fuel economy. It costs around $375 to fix.
5. Misfiring spark plugs Spark plugs are small but essential, since they make the car go by igniting the compressed fuel in an internal combustion engine. Misfiring spark plugs can affect engine power and fuel economy and can also damage the catalytic converter. You can replace spark plugs yourself for as little as $10 or pay $300 for a technician to do it.
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The oxygen sensors in front and behind the converter are reporting too similar
of readings
Possible solutions:
Check for exhaust leaks at the manifold, pipes, catalytic converter.
Replace Coolant Temperature Sensor
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor
in front of the catalytic converter normally has a fluctuating waveform. The
waveform of the sensor behind the converter should be more steady).
if u have one oxygen sensor then u need to take a deep look at the bottom of ur car it will be somewhere at the Exhaust pipe
if u have a catalytic converter then u will have two oxygen sensors one before the catalytic converter & the other will be after the catalytic converter.
Note: the catalytic converter is located at after a little bit of beginning in Exhaust pipe.
usually if you start to hear a rumble, and by rumble i mean it sounds like a bunch of pieces of metal are clanking around in your exhaust then the catalytic converter needs to be repaired. It could also be the oxygen sensor which is located on top of the converter. Volvo did an interesting job of having them sit on top of each other.
YEAH MAN I KNOW WHAT YOU ME, THOSE DARN COMPUTER ARE WAY TO SMART.. THERES NOTHING WRONG, BUT YOU CAN TAKE THE TRUCK TO A GM DEALER AND THEY CAN FLASH THE COMPTUER, BUT THE ONLY DOWNFALL IS THAT THE CHECK ENGINE LIGHT WILL NEVER WORK AGAIN.. SO ITS YOUR CALL..GOOD LUCK KEITH..
did you use a factory cat converter?
what codes do you have?
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