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2004 Buick Lesabre P0101 and P0404: Stalls After Restart, MAF Sensor Issues

Model: 2004 Buick Lesabre Fault Code: P0101 Posted: 2018-02-25 12:51

My 2004 Buick Lesabre 3.8L engine died while driving on the highway. It was towed home and I connected a MODIS scanner. The vehicle initially showed P0101 (Mass Airflow Sensor Range/Performance Problem). After clearing the code, it started and ran normally for a short time. However, the next day, the same issue returned with an additional code: P0404 (Exhaust Gas Recirculation System Performance Issue). The MAF sensor appears to be functioning within normal range in data readings—idle around 6–7 g/s, and at 55 mph it reads about 18.78 g/s. I have cleaned the MAF sensor with no improvement. The vehicle stalls intermittently, especially during idle or light load conditions. I’ve cleared the codes multiple times, and the car runs fine after each reset—only to stall again later. This behavior suggests a potential issue with sensor feedback or engine control logic. Key data points from my test drive: - Idle MAF: 6.5–7.0 g/s - WOT (Wide Open Throttle) MAF: Not tested directly, but at 80% load, MAF should reach ~120 g/s - Short-term fuel trim: -1 - Long-term fuel trim: -2 - IAC position: 97% - Engine load: 34% I’m seeking advice on possible root causes. Could the issue be related to a faulty MAP (Manifold Absolute Pressure) sensor? The vehicle doesn’t show a P0102 or map-related code, but stalling and intermittent MAF errors suggest a deeper system fault. Additional thoughts: - Does the engine stall at low load (idle/cruising), high load, or both? - Are fuel trims (LT+ST) stable under load? If they drift beyond ±10% from idle to full throttle, that could indicate MAF or MAP sensor inaccuracies. - Could EGR valve opening cause stalling at low loads? I’ve tried unplugging the MAF—vehicle won’t start. I later replaced the MAP sensor based on advice from a retired technician and have had no stalls for 30 miles. While I didn’t see a map sensor fault code, this change appears to resolve the issue. Any further insights or diagnostics would be greatly appreciated.

Related fault codes

P0101P0404

Comments (6)

Anonymous 2018-02-25 15:36

Please share the MAF sensor range in grams per second (g/s). At idle, it should typically read around 4 g/s. Under wide open throttle (WOT), expect values near 120 g/s. Also, please provide freeze frame data for both P0101 and P0404 errors to help diagnose the issue.

Anonymous 2018-02-25 17:26

I just completed a test drive. The vehicle stalled twice, and each time it showed P0101. At 55 mph, MAF read 18.78 g/s. Idle MAF was in the high 6s to mid-7s range. I’m not familiar with WOT—does that mean full throttle? I’ve also noted map value at 6.4, short-term fuel trim at -1, long-term at -2, IAC position at 97%, and engine load at 34%. Let me know if you need additional data—I appreciate your help!

Anonymous 2018-02-25 17:42

After another test drive, the vehicle stalled twice and only showed P0101 both times. In real-time engine data, MAF at idle was just over 4 g/s—within normal range.

Anonymous 2018-02-26 00:01

MAF reading of 4 g/s at idle is normal. Does the sensor increase to around 120 g/s under wide open throttle (WOT) conditions? Monitor both long-term and short-term fuel trims (LT+ST) across engine loads—values should stay within ±10% of idle to full load. The engine stalling could occur at low loads (idle or cruising), high loads, or both. Freeze frame data for P0101 is essential—it should show MAF value, engine load, and fuel trims when the code was set. An open EGR valve can cause stalling under light loads. A faulty MAF sensor may also trigger stalling and false P0101 codes. A simple test: try disconnecting the MAF sensor—does the vehicle still stall or fail to start? This helps isolate whether the issue is with MAF input or downstream control logic.

Anonymous 2018-02-28 19:20

I did some research and found another owner with identical symptoms. He replaced the MAP (Manifold Absolute Pressure) sensor based on advice from a retired technician, and the problem was fully resolved. I tried unplugging the MAF—vehicle wouldn’t start at all. After replacing the MAP sensor, the car ran for 30 miles without stalling. I never saw a P0102 or map-related code, but this change fixed the issue. Thanks again for your guidance!

Anonymous 2018-03-01 11:52

Thanks for the follow-up. For future reference: The barometric pressure (BARO) used to calculate MAF values is initially derived from the MAP sensor when the key is turned on. A high resistance in the ground circuit of the MAP sensor can trigger P0101. Perform an exhaust backpressure test to check for catalytic converter blockage—this could contribute to P0404 symptoms. More details: https://www.autozone.com/p0101