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P0054 Fault on 2008 Buick La Crosse 3.8L: Occurs Every Other Cold Start After Exhaust Replacement

Model: 2008 Buick La Crosse Fault Code: P0054 Posted: 2018-07-20 06:37

I own a 2008 Buick La Crosse with a 3.8L engine. After replacing the catalytic converter and resonator due to exhaust system failure, I also installed a new O2 sensor as part of the repair. Since then, the vehicle has started exhibiting a recurring issue: the P0054 diagnostic trouble code appears only on cold starts—specifically every other morning after an overnight stop. For example, if the P0054 code activates today during a cold start, I clear it and the code does not return until the next day's second cold start. This pattern is consistent: it occurs exactly every other morning. The issue began appearing shortly after the exhaust system was replaced. I'm seeking expert insight into why this intermittent fault would only manifest on alternate mornings and whether it could be related to sensor heater resistance, wiring, or a learned PCM value. Any advice on diagnosing or resolving P0054 in this specific setup is greatly appreciated.

Related fault codes

P0054

Comments (6)

Anonymous 2018-07-20 07:23

Please confirm which O2 sensor was replaced—specifically the heater resistance of Bank 1 Sensor 2 should be measured and compared to other sensors for consistency.

Anonymous 2018-07-20 08:49

Thanks for the response, Mode01. I replaced Bank 1 Sensor 2 with a Bosch four-wire O2 sensor. I have a digital multimeter (DVOM), but I don't know the pinout of the sensor. Any guidance on how to test it would be helpful.

Anonymous 2018-07-20 11:12

The P0054 code is typically triggered when the Powertrain Control Module (PCM) detects an abnormal heater resistance in Bank 1 Sensor 2. Here’s a step-by-step approach: 1. Disconnect both battery terminals and hold them together for at least two minutes to fully discharge the PCM's internal capacitors. This clears learned values that may be causing false readings. 2. Measure the heater resistance of both front and rear O2 sensors. While Bosch is a reliable brand, it’s not GM-specific. If there’s a significant difference between the sensors, test a Delphi sensor (often with white heater wires) for comparison. If the Delphi sensor's resistance matches the front sensor more closely, replace the Bosch one. 3. If both sensors show similar resistance values, inspect wiring from PCM pin 8 (gray wire) to the sensor and from the power/ground relay in the fuse box (pink/black wire) to ensure proper signal and ground connections.

Anonymous 2018-07-20 12:24

Thank you for the detailed advice. I disconnected the positive battery cable a few nights ago, but only for about one minute. The P0054 code still appears. I will follow your recommendations and update this thread next week with results.

Anonymous 2018-07-20 12:28

Be sure to disconnect both battery terminals and hold them together for at least two minutes—this ensures full discharge of the PCM’s internal capacitors and helps reset learned parameters.

Anonymous 2018-09-12 17:14

I recently installed a Denso O2 sensor. The measured heater resistance was 15.4 ohms. The original Bosch sensor read 8.5 ohms. After the replacement, the P0054 code no longer appears. According to technical references, acceptable heater resistance for Bank 1 Sensor 2 should fall between 11 and 21 ohms—this confirms that the Denso sensor is within specification and resolves the issue.