I get engine light, borrowed neighbors DTC reader get code P0136, could bad gas cap cause the eror?

gas cap code p0449 ??? This is not a gas cap code ! DTC P0449: Evaporative Emission (EVAP) Vent Solenoid Control Circuit.. your best bet , take it to a qualified chevy repair shop .


Wells EVAP Training with Sgt Tech P0440 P0441 P0442 etc

There are two sensors on that car, they are installed with a modification to the wiring unless you use OEM, Check your connections but it is most likely a bad upstream sensor. They both should be changed at the same time. They wear out and have a finite life.

P0136 - Oxygen O2 Sensor Circuit Low Voltage

Means that either your O2 sensor needs replacement, or the wires to it are going bad.

Many different issues or problems cause the check engine light to come on. You have to get the codes out with a code reader. These codes narrow the problem down to specific area. Then only a few parts need to be checked out to see which ones are good or bad. A loose gas cap or a gas cap with a bad seal can cause the check light to come on. This is the first thing to check.

The check engine light will stay on until you reset it with a code reader . Do that and see if any other codes come up.

P0442 FORD - Evaporative Emission System Leak Detected Small Leak

Possible causes- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
P0136 - O2 Sensor Circuit Malfunction Bank 1 Sensor 2
Possible causes- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Faulty Rear Heated Oxygen Sensor Bank 1
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks

P0141 FORD - O2 Heater Circuit Bank 1 Sensor 2

Possible causes- Faulty Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit fuse
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit open shorted to ground
- Heated Oxygen Sensor (H2OS) Bank 1 Sensor 2 circuit poor electrical connection
- Faulty Engine Control Module (ECM)

Hi there:
Both generic codes refer at Oxygen Sensors, an HO2S that responds too slowly is most likely defective. In order to solve it just replace the HO2S; check there description and diagnosis:
- DTC P0136 - O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)
- DTC P0153 - O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.


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Sorry, but there is no "sensor at the fuel cap". Therefore, there is no code that says "sensor at the fuel cap". There is, however, a Diagnostic Test Code (DTC) That indicates a possible problem with the fuel cap.
(HINT: When you want information on codes, it is usually wise to include the code number that you are getting - that way, it can be looked up, instead of GUESSING at what the problem is from a code description that some generic code reader is telling you..)
DTC P0457 is defined by SAE J2012 as "Evaporative Emission System Leak Detected (fuel cap loose/off)"

At this point, I am ASSUMING this is the code you got.

This DTC is set when the Powertrain Control Module (PCM) detects that there is an in-tank pressure drop that is more than 7in. H2O within 30 seconds directly after refueling, or there is excessive purge (fuel Vapor) flow more than .06 lbs. per minute. Possible causes are:
> Fuel filler cap not installed after refueling
> Fuel filler cap loose or cross-threaded

There are other malfunctions that can also cause this code to set, but it will be accompanied by other codes indicating other possible failures.
If there are no other Evaporative Emissions System codes present, then there is most likely a problem with the way your fuel cap was put on the last time you got fuel.

Check your fuel cap and make sure it is on correctly and is tight.

sad to say sir that how to clear the code is not easy in manual clearing, you need diagnostic tool to clear the dtc, but some dtc will cleared by 20-50 consecutive warm up if no other trouble code detected by the computer

Just disconnect the battery (negative terminal) and turn the headlight switch on for about 15 minutes. This should reset the PCM. Otherwise go to Advance and have them hookup the code reader and reset the codes. Thanks