[Innovator]

I have been getting intermittent P codes concerning the front O2 sensor. Occasionally it throws a cat sensor code, but rarely. It is only P0154 (Circuit Insufficient Activity Bank 2 Sensor 1) 95% of the time but occasionally throws other codes related to that sensor ALONG with P0154. Whether it is one code or a few, they trigger at the same time. After clearing I might not see it again for minutes or for several days.

Today it did throw a P0174 (Fuel Trim System Lean Bank 2) along with the other codes relevant to the front sensor. I did replace this sensor (with a cheapy) about 2k miles ago just as preventative maintenance while I was doing other work. However I am wondering if this is an injector issue with that bank?

Engine runs damn near perfect, once in a great while I can barely detect a little lapse in power, like a misfire but very subtle. I have spare injectors, maybe I should just swap them out one at a time and drive until the codes stops? So... sensor or an injector, anyone think that anything else is at play here?

 

[carnut]

Have you thought about a thermostat letting the engine run too cool? Without fault tracing this code in the factory service manual, you'll throw parts at it. You can monitor the engine temp thru on board diagnostics. It should be 95 to 105 Celsius within 2 to 3 miles of driving. You can also monitor the switching of the Oxy. sensor rich to lean to confirm quick response of the sensor. And be specific on which Cadillac, the 95 or the 99?

 

[Innovator]

'99 Northstar

Yes, I was going to test COLD sensor resistance, from my research it should be around 50 ohm if OK. Did not consider a temperature issue due to isolation of the codes, temp needle location is OK and code only occurs after 10+ miles of driving, though I did not mention that previously. I have no intention of throwing parts but I do have a bag of spare injectors.

 

[carnut]

I meant engine temp, not cold resistance of the OXY. sensor. Codes never diagnose an issue, they pin point the area to investigate. Do you have the factory service manual? Are you familiar with monitoring systems within the on board diagnostics?