2002 Ford Ranger Repeatedly Shows P1132 and P1152 O2 Sensor Fault Codes
My 2002 Ford Ranger is consistently displaying diagnostic trouble codes P1132 and P1152. I recently replaced the oxygen sensor on the upstream side of the exhaust. After the replacement, the codes disappeared for a few miles but returned shortly after with the same values. The issue persists across both banks. I'm looking for reliable troubleshooting steps to resolve this recurring problem.
Both engine banks show rich readings — are there any other diagnostic codes present? Has there been recent maintenance or modifications? Check the oxygen sensor voltage levels; if stuck high, what is the reading? What are the fuel trim values? Try introducing a vacuum leak and observe if the sensor voltage drops. Also verify the air filter condition — is it appropriate for the vehicle's age and usage? Ensure there’s no blockage in the intake ducting and clean the MAF sensor. Perform a fuel pressure test, then conduct a KOEO (Key Off Engine On) check to observe any pressure drop.