1998 Buick Lesabre P0108 P0121 P0102 - Engine Dies After 30 Minutes, Starts Again Then Cuts Off
My 1998 Buick Lesabre started running after I replaced the fuel pump, but only runs for 20 to 30 minutes before suddenly cutting off. Even after replacing the faulty throttle hose, the issue persists. When driving for about 30 minutes, the engine shuts down completely. After letting it sit for 5 minutes, it starts again and runs for approximately 10 to 60 seconds before cutting out. Before the fuel pump repair, the car would fail to start and repeatedly shut off. Since installing the new fuel pump, it now starts every time but consistently dies mid-drive. The check engine light is on with fault codes P0108, P0121, and P0102. I suspect there may be a sensor or wiring issue affecting the throttle position or manifold absolute pressure readings. A diagnostic scan to read live voltage data from these sensors would help identify whether the signals are accurate or corrupted.
The fault codes P0108, P0121, and P0102 suggest potential issues with sensor readings in the intake system. P0108 indicates a manifold absolute pressure (MAP) sensor voltage issue, P0121 points to an incorrect throttle position sensor reading, and P0102 suggests a problem with the throttle position sensor or related circuitry. These codes often stem from wiring faults, loose connections, or faulty sensors. Using an OBD2 scanner to monitor live data—such as actual voltage readings from the MAP and throttle position sensors—can help confirm whether the signals are within expected ranges. This would provide clearer insight into whether the issue is electrical or sensor-related.