P0137 Fault on 2000 Buick Regal 3.8L V6 Automatic: Engine Dies at High Speed and Stalls at Idle
My 2000 Buick Regal with a 3.8L V6 engine and automatic transmission has been experiencing two recurring issues over the past several months. First, while driving, the engine suddenly dies on the road—though it typically restarts immediately and runs normally for days afterward. This issue appeared to occur more frequently when the fuel tank was low, so I replaced the fuel filter, which temporarily resolved the problem for about two months. Secondly, when idling in park, the engine stalls repeatedly. In most cases, it starts right away and can run smoothly for several days before recurring. Recently, both issues have returned. Until today, I was unable to retrieve any diagnostic trouble codes (DTCs) from the OBD2 scanner. The only code detected is P0137. I'm seeking advice on what could be causing this issue—especially given that the engine behavior seems inconsistent and intermittent.
The P0137 code indicates a low signal from the Heated Oxygen Sensor (HO2S) 1/2, typically below 10mV. This can be caused by several factors including HO2S wiring faults, a failed sensor, low fuel pressure, malfunctioning fuel injectors, vacuum leaks, exhaust leaks, MAF sensor issues, or water in the fuel. I recommend checking the fuel pressure—low pressure may point to a failing fuel pump. Also inspect for any vacuum leaks and verify that all HO2S sensors are functioning properly. As a diagnostic step, try disconnecting the MAF sensor; if the stalling stops, it suggests a faulty MAF sensor, which should then be replaced. Please update with your findings after performing these checks.