still chasing a p0420 code, any techs with some ideas?

[gshadow325]

yes, i have search and search. i know with my volvo a going bad coolant temp sensor will make the car run rich but the ecu compensates for it.

Come to the conclusion. that it will come on with cold starts aka in the morning. if i take a drive for anything 15+ miles and restart, the p0420 code goes away. until the truck cools down. going to check resistance of the front O2 in the morning when the truck is cool.

info on my truck
new denso rear bank one sensor
new dealer red box front bank one sensor
new gas cap

both replaced around 1500 miles ago

help?

 

[CXS]

Since your O2 sensors are new and you're still getting PO420 you might want to see if the cat is bad but be cautious. I replaced my cat and still got the PO420 with new sensors and the new cat.

A couple ideas, make sure the sensors are tight and check for exhaust leaks. I eventually found a coupling gasket leak in mine and it took care of the error returning and returning and returning.

I never noticed the leak until I drove along a cement wall while accelerating and then it was pretty obvious. I now have a habit of stomping on it now and then in similar situations to listen for leaks. One more thing for an old guy to do to compensate for failing hearing!

 

[cabowally]

Without any other DTC tripping it pretty much has to be one or both of the sensors, an exhaust leak or cat problems.

Get the FSM if you don't have it and look for the file named 0060037.pdf under the SFI System sub-directory. Has full diagnostic procedure and testing parameters.


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what he said x2. got distracted looking up the file name.....

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Hey: Seafoaming has been such a hot topic lately maybe you'd see a smokey leak...?

 

[gshadow325]

thanks for the replies guys.

first i dont think its a exhaust leak, i know that signature sound when i hear it.
second i downloaded the fsm. dont know what file you are referring to.
third i think might be a fuel injector might be clogged

 

[gshadow325]

Without any other DTC tripping it pretty much has to be one or both of the sensors, an exhaust leak or cat problems.

Get the FSM if you don't have it and look for the file named 0060037.pdf under the SFI System sub-directory. Has full diagnostic procedure and testing parameters.


^
||

what he said x2. got distracted looking up the file name.....

.

Hey: Seafoaming has been such a hot topic lately maybe you'd see a smokey leak...?

ok, looked up what you said. it says suspect the cat going bad. well i suspect a injector leaking. i did change the plugs a few weeks ago and found one of the plugs not looking like the others. so when i told this to my most trusted mechanic friend, we bounce issues off each other when we are stumped....he says its probably a injector leaking and the ecu is trying to compensate and lean the truck out since i told him the plug looked whiter than the other ones.

 

[cabowally]

The manual's fuel sub-directory has a fuel injector section with 3 files. One has the testing procedures for fuel injectors.


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