I've heard that cleaning an oxygen (O2) sensor can sometimes avoid the need for replacement. Is this a viable solution for a 1999 Dodge Ram with a PO138 code? Does cleaning actually resolve the issue, or is it just a temporary fix?
Is the O2 sensor in question the upstream or downstream sensor? This affects how we interpret the fault and what part should be replaced.
good question which does the code reader or code definition in the trouble code link say it is? you don't figure you need to replace both? care to explain why not?
Based on my understanding, I believe the O2 sensor in question is the one after the catalytic converter — Sensor 2. The diagnostic code shows Bank 1, Sensor 2. I had the first (upstream) sensor replaced over a year ago due to chafed wire insulation causing a short. Now I'm trying to confirm whether I should replace the downstream sensor as well, just to be absolutely sure. Since these sensors are non-refundable, I want to avoid buying the wrong part. Thanks for the help!
I've heard of people attempting to clean their O2 sensors — but in practice, it rarely works. Most O2 sensors fail due to heater element failure, which isn't caused by dirt or buildup. It's a mechanical issue that simply wears out over time. Given the age of this truck, I'm surprised it hasn't been replaced already. For reliability and proper diagnostics, I'd recommend installing new upstream and downstream O2 sensors from the dealer. The Bosch sensors available at most auto parts stores often have faulty heater elements that can continue to trigger a PO138 code.