P0420 diagnosis with tactrix cable

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P0420 diagnosis with tactrix cable

Postby gui67 » Thu Sep 07, 2017 5:55 am

Hello,

My 05 Spec-B has a P0420 code since several weeks.
I tried to datalog with a tactrix cable, hoping to see where the problem comes from, between the front O2 sensors, the cat and the rear O2 sensors, or from somewhere else...

The A/F sensors #1 and #2 are always equal, richens at high load and RPM, stable at 14.7 in cruise. (I think these are the front O2 sensors, could you please confirm?)

The other sensors are called front sensor #1 and #2 in Romraider datalogger but I suspect these are the rear ones, having a value between 0V and 1V, they oscillate nearly at the same frequency and amplitude in cruise.

I also logged A/F correction and learning, but I cannot say from these values what is going wrong.
Here are examples of log:
Image

Image

Are there some other parameters which O should look at?
When I reset the ECU, the Error code will come again sometimes after 10 minutes, sometimes after 4 or 5 days. It depends. I never managed to log the moment where the code appears. Should I try to reset the error and log until the CEL lights?
Or would you have other advices?
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Re: P0420 diagnosis with tactrix cable

Postby jslayz » Thu Sep 07, 2017 9:57 am

Red rear does not seem as sensitive... just looks like it doesnt track with the one in the other bank??
What do the team think
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Re: P0420 diagnosis with tactrix cable

Postby gui67 » Thu Sep 07, 2017 2:31 pm

Thanks for your answer
Yes, the red one is sometime a little bit different then the white, it seems like sometimes it does not react so quickly.
Would that be enough to trigger the P0420 code?
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Re: P0420 diagnosis with tactrix cable

Postby jslayz » Thu Sep 07, 2017 11:57 pm

Removing the sensors and measuring the impedance will tell you.

I think in the FSM there are some ohm tolerances listed
CURRENT - ATP GTX 3576 - 22psi - 283.7awkw
OLD - Dom 1.5Xtr - Last dyno 254ahkw, previous 238ahkw, first 224awkw.
My journey thread: http://forum.liberty.asn.au/viewtopic.php?f=10&t=15523
My Lib Pics here: http://forum.liberty.asn.au/viewtopic.php?f=10&t=15523&start=570#p370656
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Re: P0420 diagnosis with tactrix cable

Postby gui67 » Sun Oct 22, 2017 4:50 pm

I replaced all 4lambda sensors because I though that with 230000km, they have certainly passed the lifetime they were designed for.
I reset the default.
It ran fine for 100km and then the P0420 code comes again.
Hat is also strange is that there is a fuel smell from the exhaust while driving with opened front window. If I smell the exhaust with the engine idling I smell nothing.


But the AFR seems ok while driving, on the datalog.
Could you please confim my assumptions that the sonsors called A/F sensor #1 and #2 are the front ones, the value is AFR. And that the sensors called front sensor #1 and#2 are in fact the rear sensors.
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Re: P0420 diagnosis with tactrix cable

Postby Mariano » Thu Nov 30, 2017 3:44 am

I have same problem now. After replacing headers and front 02 sensor, code started. My problem is bank 1 rear sensor, which is right side one. I was thinking to change bank 1 and 2 sensor positions so I can make sure it is sensor fault. Cats were visibly looking ok and spotless so I dont think thats the problem. Front 02 A/F sensors will fluctuate between 0-1v.
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Re: P0420 diagnosis with tactrix cable

Postby KiDo_Tuning » Wed Dec 06, 2017 6:38 pm

Turn it off in the tune.
Issue is Heater Element wiring loom not the actual sensor.
KiDo Racing Tunes Info: HERE

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