Did I leaves something disconnected?

[Oldmactech]

My 3.0 won’t complete the OBDii diagnostic cycle to pass emissions in GA. It completes 7 of 8 cycles but after nearly 400 miles, numerous starts, all types of driving I still get the catalyst monitor incomplete but no codes. Last month a got a bank one before catalyst check engine error but I cleared it and reset the adaptations.

As a senior I am exempt from exemptions but if I tried to sell it would need to pass.

This car had a shade tree head gasket done 1200 miles ago, is it possible I left something disconnected or have one of the O2’s reversed in their places causing it not to complete the diagnostic cycle?

Thanks.


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[Overboost]

Originally Posted by Oldmactech

My 3.0 won’t complete the OBDii diagnostic cycle to pass emissions in GA. It completes 7 of 8 cycles but after nearly 400 miles, numerous starts, all types of driving I still get the catalyst monitor incomplete but no codes. Last month a got a bank one before catalyst check engine error but I cleared it and reset the adaptations.

As a senior I am exempt from exemptions but if I tried to sell it would need to pass.

This car had a shade tree head gasket done 1200 miles ago, is it possible I left something disconnected or have one of the O2’s reversed in their places causing it not to complete the diagnostic cycle?

Thanks.


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If you had reversed the lambda connectors you would have all kinds of codes so I doubt that is it. Since you had the head gasket failure and probably pushed a lot of water down the exhaust it could have compromised the sensor(s). I would have a good look at your LTFT and STFT values and check you lambda voltage values. They are cheap enough to just replace if you have over 125,000 miles I recommend it.

[Oldmactech]

Lambda Sensor = O2sensor?


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[Overboost]

Originally Posted by Oldmactech

Lambda Sensor = O2sensor?


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Yes same thing

[Oldmactech]

Thanks, sure I have the manifold sensors correct, might have crossed the Dow streams? Matter?

Confused that after 100 miles or so it would either complete the cycle or throw a code if not good.


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[Overboost]

Originally Posted by Oldmactech

Thanks, sure I have the manifold sensors correct, might have crossed the Dow streams? Matter?

Confused that after 100 miles or so it would either complete the cycle or throw a code if not good.


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You would have codes if any of the 4 were reversed. How old are those sensors? They are only around $50/piece and are really easy to replace. I would replace the upstream ones.

[Overboost]

Get up early tomorrow morning and get on the 85/75 or whatever highway is near you and set to the cruise control at 50 MPH for 15 minutes. DO NOT exceed 3000 RPM or go below 40 MPH or over 60 MPH or it will reset again. 15 minutes at that speed should clear the catalyst monitor.

[Overboost]

At 95K they should still be fine unless they were compromised by your head gasket issues. I don't know if you had water out the exhaust or if you dumped a lot of coolant down the exhaust when you removed your head.

[crystalworks]

Originally Posted by Overboost

You would have codes if any of the 4 were reversed. How old are those sensors? They are only around $50/piece and are really easy to replace. I would replace the upstream ones.

I replaced all 4 of mine. Had poor results with the $50 Bosch splice in sensors. Ended up having to go for the $100 plug and play Bosch units due to fighting o2 codes for a few months. Resetting adaptations was key though after replacing all 4. Just my experience though.

[Overboost]

Mu precatalyst sensors were just under $65 from FCP Euro. Not sure if the V8 uses a different sensor thank the 3.0

https://www.fcpeuro.com/products/bmw...or-bosch-13477