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2000 Buick Regal LS P0131 Code: Acceleration Issues and MAP Sensor Diagnosis

Model: Regal Fault Code: P0131 Posted: 2008-04-16 13:53

Hi, I own a 2000 Buick Regal LS with 71,000 miles. Recently, the car has become unresponsive during acceleration. When I press the accelerator pedal, RPMs increase slowly but the vehicle does not gain speed—this behavior is intermittent but has worsened over time. The check engine light comes on approximately once a month, and when it does, I retrieve code P0131 (O2 Sensor Heater Circuit Low Voltage) and clear it. I've already replaced both the oxygen sensor and all six spark plugs. Fuel pressure readings are normal, and TPS resistance responds correctly when the accelerator cable is pulled. All three coil resistances also check out as expected. Additional symptoms include difficulty maintaining speed on inclines—when cruising at 70 mph, the car drops to around 60 mph before downshifting, with RPMs spiking to 4500 to regain speed. I'm considering a MAP sensor replacement, as I've heard it might be related. Since my wife drives an Impala with a 3800 engine (which shares similar components), I plan to swap the MAP sensor between vehicles to test if that resolves the issue. Could this be a faulty MAP sensor? Are there any diagnostic steps I can take before replacing parts? Thanks, Nathan

Related fault codes
P0131
Comments (8)
Anonymous 2008-04-16 15:26

Could a clogged catalytic converter be contributing to the acceleration issues and P0131 code? Is this common in older Buick Regal LS models?

Anonymous 2008-04-16 19:27

What's the best way to test for a clogged catalytic converter at home? Can I do it myself without special tools?

Anonymous 2008-04-17 04:59

You can use a vacuum gauge connected to an intake port, or remove the oxygen sensor upstream of the catalytic converter and attach a pressure adapter to check for positive exhaust pressure.

Anonymous 2008-04-21 07:28

New Development: Following advice from a friend, I unplugged my MAP sensor while driving. Immediately, the non-acceleration issue disappeared—acceleration became smooth and responsive. After replacing the MAP sensor with a new one for $60, the problem returned. The car still doesn't accelerate properly under normal conditions. This suggests either a faulty wiring harness or an ECU fault. Are there any specific diagnostic tests to isolate whether it's the sensor, wiring, or the engine control unit? Any recommendations? Thanks, Nathan

Anonymous 2008-04-22 15:06

When the MAP sensor is disconnected, the ECU defaults to a base fuel map that delivers richer fuel mixtures to protect the engine. This explains why performance improves temporarily. However, you should also check for vacuum leaks, low fuel pressure, or injector issues—these can mimic similar symptoms.

Anonymous 2008-04-22 18:44

Yes, the car runs much more powerfully when the MAP sensor is disconnected—it's running rich and protected from potential damage.

Anonymous 2008-04-22 20:08

I’ve tested for vacuum leaks with my ears and don’t hear any. Are there other methods to detect vacuum leaks besides listening? Any reliable DIY techniques? Thanks, Nathan

Anonymous 2008-04-23 04:54

Listening is one of the least effective methods! Search online or check automotive forums for detailed guides—many Haynes and Chilton manuals cover vacuum leak diagnosis in early chapters.