P1516 on Buick: How to Diagnose & Fix
Throttle Actuator Control (TAC) Module — Throttle Actuator Position Performance (GM)
1 Buick model · 1 documented issue · $250-$600 repair
P1516 on Buick by model: symptoms, diagnosis and fix
A failing electronic throttle body or throttle position sensor triggers a 'Reduced Engine Power' message and limp mode, with rough or surging idle and hesitant acceleration. The condition is common enough that GM issued a special coverage adjustment extending the throttle body warranty on some 2009-2011 cars.
Common Symptoms
- 'Reduced Engine Power' message
- Limp mode / very limited acceleration
- Rough or surging idle, RPM jumping
- Hesitation on acceleration
- Check engine light
How to Fix
Clean the throttle body first; if the TPS/electronic throttle body has failed, replace it and perform the required throttle relearn so the computer sets correct idle and full-throttle positions. GM Special Coverage extended this to 10 years / 120,000 miles on covered 2009-2011 models.
Sources for this issue (1)
P1516 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1516 mean on a Buick?
P1516 stands for "Throttle Actuator Control (TAC) Module — Throttle Actuator Position Performance (GM)." P1516 is a manufacturer-specific code used mainly by General Motors vehicles (Chevrolet, GMC, Buick, Cadillac, Hummer, Saturn), where it means the electronic throttle system's actual throttle plate position doesn't match what the computer commanded. In a drive-by-wire system, the ECM reads the accelerator pedal sensors and drives a motor on the throttle body to open the throttle; if the throttle position sensors report a position that disagrees with the command for more than about a second, this code sets. Drivers typically see a "Engine Power Reduced" message with the check engine light, and the vehicle drops into limp mode with sluggish, limited acceleration; some trucks set the code with no symptoms at all. Because throttle control directly affects your ability to accelerate, it should be diagnosed promptly rather than driven around. Note that the definition differs by manufacturer: Ford uses P1516 for an Intake Manifold Runner Control (IMRC) input error on Bank 1, while Honda/Acura use a throttle actuator position definition similar to GM's. On Buick it is documented across 1 model: Lucerne.
What are the most common causes of P1516?
The most common causes of P1516 are: Faulty throttle body / throttle actuator motor (the most common fix on GM trucks and SUVs), Dirty or carbon-fouled throttle body causing the throttle plate to stick or move erratically, Poor engine ground connections (corroded GM ground points G103/G104 causing voltage drop above 0.1V), Damaged wiring or corroded connectors in the TAC motor control or throttle position sensor circuits, Faulty throttle position sensor(s) on the throttle body, Failed stand-alone TAC module (separate module on 1999–2005 GM trucks), ECM/PCM fault, or a needed throttle relearn after cleaning or battery disconnect. The specific cause varies by vehicle.
How much does it cost to fix P1516 on a Buick?
Published repair estimates on Buick range from $250 to $600 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P1516 on a different make?
View P1516 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.