Codes P0456, P0431 and P0456

IFYUSER

MEMBER
2003 VOLKSWAGEN PASSAT
2.8L
6 CYL
4WD
AUTOMATIC
180,000 MILES

The catalytic converter code turns off sometimes on and off and the misfire code is intermittent and the evap code sometimes turns off. The heater core hose exploded and leaked antifreeze to the left side of the engine. All three the o2 sensor harness purge valve harness and cylinder three wire are near where it leaked. Could the antifreeze have caused the ECU to short causing these codes? I already changed the purge valve, evap pump, hose to purge valve, and vapor canister. And had it smoked tested twice and they can't find a leak. Injector. Wires, distributor, and o2 sensor and still get the codes.

Saturday, December 11th, 2021 AT 11:40 PM

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If these codes are intermittent, it is possible. However, I would not replace the ECM based on just this info.

So that means we need to use this guide to help test the system.

I attached the testing for the evap code as that is the easiest to follow through. If there are no leaks and you have replaced the purge already then, the ECM is a possibility.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Take a look at the testing below and if that leads you to replacing the ECM then do that and retest to see if any of the other codes come back as well.

Let me know if you have questions on this.

Thanks

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