PO300 and PO152 Fault Codes - 2002 Chrysler Concord 3.5L Engine Diagnosis
2002 Chrysler Concord with a 3.5L engine, original owner, 58,000 miles. The check engine light has been on and diagnostic codes PO155, PO153, and PO340 have appeared. I replaced the spark plugs, air filter, used injector cleaner, replaced bank 2 oxygen sensor #1 (B2S1), and installed a new timing belt. After clearing the codes, I drove the vehicle for two days—then the check engine light returned with new codes: PO155 and later PO300 and PO152. The previous O2 sensor supplier indicated the B2S1 sensor was faulty and provided a replacement; however, after installation, the issue persisted. Next week, the check engine light came back with codes PO300 and PO152. I'm seeking advice on what steps to take next. Any insights into potential causes or troubleshooting procedures? Thanks, Jim.
To properly diagnose this issue, we need to check the voltage reading from the B2S1 oxygen sensor (bank 2, sensor 1). Do you have an OBD2 scanner available? Note that the PO300 code did not appear before the spark plug replacement—this raises a concern about the brand of spark plugs used. Spark plug brands matter significantly; avoid generic or low-quality brands. Also, ensure the B2S1 oxygen sensor wiring is properly connected and not using an inexpensive, non- OEM-style wire, as these can cause intermittent faults.