Chevy Code P1516: Meaning, Causes & How to Fix It
Code P1516 means the Throttle Actuator Control (TAC) module commanded the throttle plate to a specific angle, but the throttle position sensors reported back a different actual position than expected. Because this affects the electronic throttle system directly, it often comes with a noticeable loss of power or limp mode.
Jump to a section: What P1516 means · Common symptoms · Common causes · Check engine grounds first · Quick reference table · FAQ
What P1516 Means
Modern GM engines use an electronic throttle body rather than a mechanical cable, with the TAC module commanding the throttle plate's position and the throttle position sensors confirming it actually moved there. When the commanded and actual positions don't match closely enough for long enough, the module logs P1516 and can restrict engine power as a safety precaution.
Common Symptoms
Engine hesitation, reduced power, occasional stalling, and the vehicle entering limp mode with limited acceleration are the most commonly reported symptoms, since this code directly affects how the engine responds to throttle input.
Common Causes
A failing throttle position sensor, a physically binding or dirty throttle valve/plate, damaged wiring in the throttle body harness, or a poor ground connection are the most frequently reported causes. A TAC module fault itself is possible but generally less common than these simpler issues.
Check Engine Grounds First
On many GM trucks specifically, cleaning the engine grounds (commonly labeled G103 and G104 in service documentation) to bare metal resolves this code surprisingly often, since even a small voltage drop across these ground points can throw off the throttle position readings enough to trigger a fault. This is worth checking before assuming a throttle body or sensor replacement is needed.
Quick Reference Table
| Step | What To Check |
|---|---|
| 1 | Clean engine grounds to bare metal |
| 2 | Inspect throttle body for dirt/binding |
| 3 | Inspect throttle body wiring harness |
| 4 | Test throttle position sensors |
| 5 | Consider TAC module or throttle body replacement |
Frequently Asked Questions
Is it safe to drive with P1516 active?
If the vehicle has entered limp mode, driving is significantly limited and it's best to have it diagnosed promptly rather than continuing to drive with restricted throttle response.
Can cleaning the throttle body fix this code?
Yes, in some cases — a dirty or gummed-up throttle plate can cause enough binding to create a position mismatch, and a proper throttle body cleaning resolves the issue without needing part replacement.
Why would a ground connection cause a throttle code?
Throttle position sensors rely on a clean, stable reference voltage and ground to report accurately; a corroded or poor ground connection can introduce enough error into the sensor signal to trigger a performance-mismatch code like P1516.
Do I need to replace the whole throttle body?
Not always — grounds, wiring, and cleaning are all worth checking first, since a full throttle body replacement is a more expensive step best reserved for when simpler causes are ruled out.
Shop the Parts Mentioned
- Wireless Scanner — confirms the code and helps monitor throttle position data live.
- Bidirectional Scanner — supports live sensor data monitoring during diagnosis.
- Taylor Battery Cable Terminal Kits — useful for addressing related ground and connection issues.
- 95-Piece Mechanics Tool Set (Metric & SAE) — for throttle body and ground access.
- 5-Piece Pro Electric Wrench Kit — speeds up throttle body removal for cleaning or inspection.