1999 Chevrolet Silverado P0137 and P0157 O2 Sensor Fault Diagnosis and Fix
I own a 1999 Chevrolet Silverado with persistent check engine light issues triggered by fault codes P0137 (O2 Sensor Circuit Malfunction - Bank 2, Sensor 1) and P0157 (O2 Sensor Circuit Malfunction - Bank 1, Sensor 1). After taking it to multiple auto shops, I'm frustrated with inconsistent diagnoses. The truck exhibits rough idling, poor running performance, especially at stop signs, and the check engine light frequently comes on and off. The previous mechanic claimed a faulty EGR valve was causing the codes, but after replacing the EGR valve twice and fuel filters, the issue persisted. I tested the EGR valve myself — it functioned correctly. A Chevrolet dealership replaced the EGR valve and stated the powertrain control module (PCM) was fine. However, after driving home, the check engine light reappeared, and now the codes P0137 and P0159 are present. I'm seeking reliable, DIY-friendly solutions to diagnose and fix these O2 sensor-related issues without relying on dealer services. Any insights or troubleshooting steps for a 1999 Silverado with these specific fault codes would be greatly appreciated.
What engine size do you have? Are there any noticeable driveability issues like rough idling, stalling, or poor acceleration? Did the check engine light appear before any repairs were done?