Check engine light code P0420
my check engine light came on after I filled gas. I got the code read and it was the code P0420 for catalytic converter. However, after I drove it a couple times the light went off. I filled gas, it went back on and as before after driving a couple times it went off. Why would it be going on and off if there was a problem?
My car has 65000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
You may have a purge valve that is leaking and causing excessive fumes to enter the intake manifold during the refuel process. When you start the vehicle, the excessive rich mixture may be causing the catalyst to overheat which will trigger the P0420 code. This will happen if, after a couple of starts, the computer does not see a problem and clears the code.
I’d recommend seeking some assistance from a certified mechanic who can diagnose your Check Engine Light first hand and fix the problem accordingly.
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Code P0420 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.
The P0420 code signals a low catalyst system efficiency. This code suggests that the oxygen levels are below the desired threshold (Bank 1), which most often results from problems with your car`s exhaust or fuel systems.
A P0420 code is set when the upstream sensor and the downstream oxygen sensor sense the catalytic converter is not doing its job. Basically, the amount of oxygen going into the converter is not being burned, and it detects it through the downstream sensor.
Yes, you may be able to fix P0420 yourself. Depending on the cause of the code, the diagnosis and the repair might be simple or might be very difficult to do at home. You might need access to a welder if you need to patch an exhaust leak. You might also cause more damage trying to repair your problem.
A common emissions code seen in the field, a P0420 trouble code indicates that the catalytic converter isn`t functioning efficiently. To work at peak efficiency, the emissions or feed gases entering the catalytic converter need to be perfectly balanced and not excessively elevated.
Because there are no driveability symptoms associated with the P0420 trouble code, it is not considered serious or dangerous to the driver. However, if the code is not addressed in a timely manner, the catalytic converter could be seriously damaged.
P0420 typically means that a converter has worn out or degraded—not obstructed or clogged. But if the case is the latter, it can lead to engine performance problems, such as a lack of power, rough idling, and stalling, which are some of the common signs of a clogged catalytic converter.
P0420 means a catalytic converter problem affecting its efficiency or a problem with the oxygen sensors. So yes, it could be a bad plug which is allowing unburnt fuel to enter the cat and eventually damaging it.
The code P0420 can be caused by the catalyst, O2 sensors before and after the catalyst. If both O2 sensors and catalyst was replaced then you may have an exhaust leak at the manifold or pipes.
If the engine is burning oil, which sounds like yours does, this can damage the catalytic converter, which can result in the P0420 DTC.
A P0420 code indicates a malfuction in your Catalytic Converter Efficiency Test due to a failing catalytic converter. However, it can also mean something else such as; Bad O2 sensor (either upstream or downstream), either the heater circuit or a stuck value. An exhaust leak which may fool the O2 sensors.
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