Durametric fault code question

[JFP in PA]

Originally Posted by sfoster13

Getting these two codes:

PO139 - Fault Code 17 - Sensor ageing behind cat converter cylinder (1-3)
PO140 - Fault Code 12 - O2 sensor behind cat converter cylinder (4-6)

Car is a 2002 S

These are just for bad 02 sensors, right? Nothing about the cat itself? Just replace the two sensors? And does behind mean before or after the cat?

Thanks for the help

Maybe, or maybe not. P0139 is indication of an aging (read dying) sensor behind the three way cat on bank 1-3. That said, P0140 is indication of an interruption of signal from the same sensor, which is often a wiring or connector issue.

I would use the Durametric to read the voltages for the sensor to see if they are in range, if they are, you may want to check its harness for problems.