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Discussion Starter · #1 · (Edited)
2014 challenger srt8
So I’m dealing with a P2097 engine code, which indicates a fault with the post catalyst fuel trim system being too rich in bank 1. I have a OBD2 scanner and it seems like the O2 sensors after the catalytic converter are on the higher side when at idle and driving...staying steady between .7-.8
The O2 sensors BEFORE the catalytic converter bounce around a lot going up and down both when at idle and driving. I have had this code before, and put in a new FACTORY o2 sensor for the bank 1 post catalytic converter and had the PCM flashed per the TSB at a independent mechanic. Didn’t get the code for a solid year and now it’s back. Need to still look under the car for any possible exhaust leaks. MPG isnt any worse this time around, it’s at 14. Last year when I had this problem it was at 11. Any suggestions? Would be highly appreciated. Thank you
 

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Could be a defective O2 sensor. Easy to access? Swap that sensor to the other side, clear codes and wait for the light to see if it goes to bank 2. An exhaust leak would make it go lean, so it would be stuck under .5v. Like .2v or less.
 

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2020 Dodge Challenger Hellraisin Scat Pack
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2014 challenger srt8
So I’m dealing with a P2097 engine code, which indicates a fault with the post catalyst fuel trim system being too rich in bank 1. I have a OBD2 scanner and it seems like the O2 sensors after the catalytic converter are on the higher side when at idle and driving...staying steady between .7-.8
The O2 sensors BEFORE the catalytic converter bounce around a lot going up and down both when at idle and driving. I have had this code before, and put in a new o2 sensor for the bank 1 post catalytic converter and had the PCM flashed per the TSB at a independent mechanic. Didn’t get the code for a solid year and now it’s back. Need to still look under the car for any possible exhaust leaks. MPG isnt any worse this time around, it’s at 14. Last year when I had this problem it was at 11. Any suggestions? Would be highly appreciated. Thank you

You may find the info at this link helpful:


The possible causes;

Faulty catalytic converter
A faulty mass air flow or manifold air pressure sensor
Defective O2 sensor/s
Burnt, chafed, broken, or disconnected wiring and/or connectors
Engine exhaust leaks

Wide bank sensors should not manifest any current swings. Thus I suspect your car's engine is fitted with narrow band sensors.

How narrow band sensors work:



As an aside, this link covers how wide band sensors work:



AFAIK, all post converter sensors are of the narrow band type.

Assuming your car engine has the narrow band sensors, the 0.7 to 0.8 volts from the post converter sensors is normal. They are signaling a low oxygen level. This means the excess oxygen that is in the exhaust gases is being used in the converter.

Actually if you observed the voltage levels with a scope and over time you would see the voltage readings vary slightly as the engine controller varies the air fuel mixture from slightly too lean to slightly too rich.

The pre converter sensors can manifest wide swings in voltage. For narrow band sensors they normally swing from a low of 0.1V to a high of 0.7V to 0.9V. At idle the swing happens about once a second. At higher RPMs several times a second.

This is the engine controller slightly varying the air fuel mixture first supplying just a slightly rich mixture then a slightly lean mixture. During the rich mixture combustion and after the exhaust gas flows into the converter where if everything is working right the converter will use trapped oxygen -- obtained during a lean combustion cycle -- to process the exhaust gases. During a lean combustion and after the exhaust gas flows into the converter where some of the oxygen is used to process the exhaust gases but the excess oxygen is trapped to be used later.

From what you post it reads at least while you are observing the sensor voltage signals they are ok even though at some point a sensor related error code is logged.

This is based on my experience normal. I had a car with an O2 sensor problem. I wanted to see the sensor acting up. I knew about when the sensor would go bad and pretty much drove around with an OBD2 scan tool connected to the car's OBD2 port with sensor voltages being displayed in "real" time.

Finally I happened to check the readings and saw the suspected sensor's voltage not at all what it should have been. The CEL came on.

But the wonky sensor didn't continue to act wonky but after a bit resumed more normal operation.

My scan tool had the ability to activate the engine controller's O2 sensor tests. I tried these tests and my memory is the tests didn't indicate a problem. But at least one other time when I used the scan tool to activate the O2 sensor tests a test came back with a result that confirmed there was a sensor problem.

That you replaced the sensor and the code stayed away for a year but has now returned suggests the replacement sensor has gone bad.

You don't say what sensor you used: Factory or a sensor "labeled" as a suitable replacement for the factory sensor.

Have to note even a genuine factory sensor can suffer from premature failure. This is why when installed by a dealer tech there is or should be a warranty on in this case the sensor.

My SOP over the years when replacing O2 sensors is to be sure to stick with the factory sensors. I get my sensors from a dealer parts counter. And I replace sensors in pairs, at least, and in some cases -- such as when one sensor generated an error code at 132K miles -- I replace all 4.

When replacing sensors it is important to avoid touching the tip.

Do not attempt to measure resistance.

Do no clean the sensor with anything.

Do not clean the sensor wiring hardness connector or the engine wiring harness connector. This can contaminate the sensor.

Do not use anti seize. Factory sensors I have bought have come with a light coating of some almost clear grease on the threads. OEM sensors (not factory sensors) I have bought have come with no signs of any thread lube.

Be sure the electrical connectors and their pins/sockets are in good condition. Be sure you fully press the two connectors together. With my cars the connectors have some kind of latch that requires the two halves be pushed together with some force to ensure this latch can snap into position to ensure the two connectors are held together.

Be sure after you connect the sensor to the wiring harness the harness wiring and sensor wiring is secured correctly and routed correctly.
 
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