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2000 Buick Regal P0131 and P0137 O2 Sensor Faults Causing Poor High-Speed Acceleration and Fuel Efficiency

Model: 2000 Regal Fault Code: P0131 Posted: 2014-04-22 18:20

I recently purchased a 2000 Buick Regal with the V6 3800 SII engine, which had only 74,000 miles on it over its 14-year lifespan. The initial test drive went smoothly, and the car appeared to be in excellent condition—until I tried driving on the freeway. The vehicle refused to exceed 60 mph, prompting me to pull off at the next exit. After a quick search, I learned about 'WOT-lag' (Wide Open Throttle delay), which is common in some V6 engines and may explain sluggish response under heavy load. I attempted a more gradual acceleration, and this time it seemed to work better. However, today while leaving the DMV, the 'Service Engine Soon' light activated. After connecting an OBD-II scanner, I received two diagnostic codes: P0131 (Oxygen Sensor Circuit Low Voltage - Bank 1, Sensor 1) and P0137 (Oxygen Sensor Circuit Low Voltage - Bank 1, Sensor 2). I suspect these failing oxygen sensors are contributing to the poor high-speed performance and extremely low fuel efficiency. Currently, I've driven 50 miles on a quarter tank of gas—equating to just 12.5 MPG, which is far below normal for this vehicle. My questions are: Is it safe to replace both O2 sensors (especially since the car needs smog certification anyway)? Will replacing them restore high-speed acceleration and normalize fuel consumption? And could these sensor failures be directly linked to the sluggish performance I'm experiencing?

Related fault codes
P0131P0137
Comments (3)
Anonymous 2014-04-23 06:49

Let's start with a can of SeaFoam injector cleaner to clean the fuel system. If you have access to an OBD-II scanner, check live data such as fuel trims and oxygen sensor voltages. Also perform a fuel pressure test using a gauge. Do not rely on 'speed shops' or aftermarket solutions like miracle magnets, cosmic air filters, lower thermostat settings, chips, or ECU programming. If parts are needed, only use AC Delco OEM components.

Anonymous 2014-04-24 06:39

The symptoms—sluggish acceleration and poor performance—are more likely due to a clogged catalytic converter or a faulty Mass Air Flow (MAF) sensor than failing oxygen sensors. A blocked cat can cause similar issues even without generating a catalytic converter DTC. In such cases, temporarily disconnecting the O2 sensor(s) and driving the vehicle may reveal whether performance improves. This test could help confirm if the issue is truly related to sensor failure.

Anonymous 2014-04-24 15:17

P0131 and P0137 indicate oxygen sensors reporting low voltage, which signals a lean air-fuel mixture—meaning too much air and not enough fuel. Since these are Bank 1 sensors (front of engine), they are part of the primary engine management system. A lean condition can directly cause poor acceleration and reduced fuel efficiency. For a 2000 Buick Regal, the fuel pump is typically expected to last around 75,000 miles; replacing it may be necessary in addition to changing the fuel filter.