2001 Chevy Tahoe 5.3L Power Loss After Tune-Up: P0151 and P0131 O2 Sensor Codes
Hello everyone, this is my first post on the forum — I'm a DIYer who's completely stumped by an issue I've been experiencing with my 2001 Chevrolet Tahoe equipped with the 5.3L V8 engine. The vehicle has approximately 130,000 miles on it. Recently, I performed a full maintenance service including replacement of spark plugs, ignition wires, upstream O2 sensors, fuel filter, fuel pump, air filter, and other standard components. I also cleaned the MAF sensor and throttle body. Despite these efforts, the car occasionally loses power during moderate acceleration — not at full throttle — and then abruptly enters a 'safe mode' state. The check engine light comes on steadily (not flashing), showing fault codes P015 or P0131. After this event, the vehicle struggles to maintain highway speeds. I have a diagnostic scanner in the car and have successfully cleared these codes while driving — after clearing them, power returns normally and the issue doesn't recur immediately. However, I'm deeply concerned about safety: I don’t want my wife and children to be in the vehicle when it suddenly loses power during traffic. I’ve captured freeze frame data from when the codes were triggered. I’m happy to share this if helpful. What could be causing this? Any suggestions for next steps would be greatly appreciated.
No modifications have been made to the vehicle. Plugs are OEM AC Delco — that detail matters. What type of OEM air filter was used? These symptoms (low power and O2 sensor issues) suggest a common root cause. I’d recommend checking the fuel trims — especially if they’re showing excessive compensation. Also, verify the upstream O2 sensor voltages — are they stable? Can you manually manipulate them (e.g., via vacuum leak or carburetor spray) to test responsiveness? A thorough vacuum leak check is essential. And don’t forget a fuel pressure test — it’s one of the most common overlooked diagnostics in these cases.