P1516 is a throttle actuator control code — the module commanded a throttle position and the throttle didn't end up where it should have. On GM V8s the cause GM documents is carbon build-up, and the repair has a second half that gets skipped constantly: after cleaning the throttle body you must perform an idle learn reset. Omit it and the concern comes straight back, now with P0121, P0506 and P0507 alongside it.
Jump to a section: What P1516 means · The special coverage myth · The two-part code form · Causes and how to confirm each · Affected vehicles · How it's diagnosed · Parts, labor and cost · Service bulletins · FAQ
What P1516 Means
P1516 lives in GM's throttle actuator control system — the electronic throttle. There is no cable from your pedal to the throttle plate; the module reads pedal position, commands a throttle angle, and then verifies through two throttle position sensors that the plate actually went there. P1516 is what it sets when the verification fails.
The important consequence: this is a performance code, not a circuit code. The wiring can be perfect and the sensors can be healthy, and P1516 will still set if the throttle plate is being physically held from reaching its commanded position — which is exactly what carbon build-up does.
The Special Coverage Myth — Read This Before Calling Your Dealer
Many pages state that P1516 is covered by GM Special Coverage 14582, or by 11273B, giving owners 10 years or 120,000 miles of free repair. We opened both documents and confirmed that is not correct.
| Programme | What it actually requires | Does P1516 qualify? |
|---|---|---|
| Special Coverage 14582 | Entry criterion is DTC P2135, P0121 or P0221 | No — P1516 is not an entry code |
| Special Coverage 11273B | Entry criterion is DTC P2135 alone | No |
GM states that if the qualifying code is absent, the repairs are not covered. So the honest position is this: if you have P1516 and P2135, you may well qualify on a covered vehicle — and those two codes do often appear together, since both come from the throttle actuator system. But P1516 on its own does not open the door, and walking into a dealer quoting the coverage number without the qualifying code will not go well.
It is still worth asking. Ask specifically whether P2135, P0121 or P0221 is present or in history, because that — not P1516 — is the question that decides who pays.
The Two-Part Code Form: P1516-XX
No GM-documented sub-types were found for P1516. The GM bulletins naming this code write it as a bare five-character DTC. Any 32-row table showing P1516-00 through -1F with distinct meanings is auto-generated boilerplate, emitted for every code on the sites that publish it, with no manufacturer attribution.
Causes of P1516 — and How to Confirm Each One
| Cause | How to confirm it | What GM says to do |
|---|---|---|
| Carbon build-up on the throttle bore and plate — the documented cause | Visual inspection with the intake duct off. GM's mechanism: carbon causes the module to increase the commanded throttle plate angle to maintain airflow, and the mismatch sets the code | Clean the throttle body per SI, then perform the idle learn reset |
| Failed throttle position sensor | The decisive test is GM's "TP Sensor 1 and 2 Agree/Disagree" scan tool parameter. Disagree means replace the throttle body | Replace the throttle body assembly |
| Throttle body assembly fault confirmed after repair | If P1516 sets again together with P2101 and/or P2176 after cleaning and the idle relearn, GM directs replacement | Replace the throttle body |
| Idle learn not performed after cleaning — a self-inflicted repeat | The concern returns after a throttle body service, now with P0121, P0506 and/or P0507 alongside | Perform the idle learn reset with a Tech 2 |
The step most people skip
GM is explicit that cleaning alone is not the repair. After cleaning, the idle learn reset must be performed, and GM even tells the technician where to find it: the Tech 2 ECM menu, under Module Set Up or Special Functions, then TAC System.
Skip it and the module is still running its learned compensation for a dirty throttle body against a clean one. GM names the result — the concern returns with P0121, P0506 and P0507. If your throttle body was cleaned and the light came back within days, this is almost certainly why.
Chevrolet Vehicles Documented for P1516
GM bulletin PIP4578B covers V8-equipped vehicles:
| Vehicle | Years |
|---|---|
| Silverado, Suburban, Tahoe | 2006–2018 |
| Avalanche | 2006–2014 |
| Corvette | 2006–2018 |
| Camaro | 2010–2018 |
| Express | 2006–2017 |
| Impala, Monte Carlo, TrailBlazer | 2006–2009 |
| Colorado | 2008–2009 |
The GMC equivalents — Sierra, Yukon, Savana, Envoy and Canyon — are covered by the same bulletin.
How P1516 Is Diagnosed
You need a Tech 2 or a scan tool with equivalent GM function access. Two things on this code are only available there: the "TP Sensor 1 and 2 Agree/Disagree" parameter that decides whether the throttle body is replaced, and the idle learn reset that completes the repair. A generic reader can show you the code and nothing that helps you act on it.
- Read all codes. Note specifically whether P2135, P0121 or P0221 is present — that determines special coverage eligibility, which is a money question before it is a diagnostic one.
- Check the TP Sensor 1 and 2 Agree/Disagree parameter. Disagree means the throttle body is replaced and the cleaning path is moot.
- If they agree, remove the intake duct and inspect the throttle bore and plate for carbon.
- Clean the throttle body per the service information procedure.
- Perform the idle learn reset via the Tech 2 ECM menu, Module Set Up or Special Functions, TAC System. This is not optional.
- Torque the throttle body fasteners to 10 N·m (89 lb in).
- Road test. If P1516 returns with P2101 or P2176, GM directs replacing the throttle body.
Parts, Labor Time and Cost
| Item | GM part number | Price | Labor operation | Time |
|---|---|---|---|---|
| Throttle position sensor kit, with clips and cover | 19259452 | $204.50 MSRP / $114.32 discounted | T5876 | 1.3 hr (1.7 hr Express / Savana) |
| TP sensor kit (alternative listing) | 19300180 | Not published | — | — |
| Throttle body assembly — Bosch | 12589056, 12631016, 12631018, 12616994, 12616995, 12631186, 12631187, 12616438 | Not published | — | — |
| Throttle body assembly — Hitachi | 12609500, 12615503, 12620183, 12615516 | Not published | 9900244 | 1.0 hr |
| TP sensor cover replacement | 19259452 | As above | 4081058 / 9900245 | 1.3 hr |
| Clear codes and note diagnosis | — | — | 4029929 / 9900243 | 0.1–0.3 hr |
An important ordering rule from GM: on vehicles with the Hitachi throttle body, GM directs fitting the sensor kit first, and replacing the throttle body only if the kit does not correct the concern. On Bosch units the sensor is not serviced separately. Identify which one you have before ordering — that decision is the difference between a $114 part and a complete assembly.
Torque spec for the throttle body fasteners is 10 N·m, or 89 lb in. That is inch-pounds, not foot-pounds; over-torquing distorts the housing.
GM Documents That Name P1516
| Document | Subject | Relevance |
|---|---|---|
| PIP4578B | Carbon build-up causing increased throttle plate angle; clean and idle learn | The main P1516 bulletin |
| Special Coverage 14582 | Throttle body / TP sensor coverage, 10 years or 120,000 miles | Entry criterion is P2135, P0121 or P0221 — not P1516 |
| Special Coverage 11273B | Earlier throttle coverage programme | Entry criterion is P2135 alone |
No NHTSA recall relates to P1516 on the models we checked.
Frequently Asked Questions
Is P1516 covered by GM's throttle body special coverage?
Not by itself. We opened both Special Coverage 14582 and 11273B and confirmed their entry criteria: P2135, P0121 or P0221 for 14582, and P2135 alone for 11273B. P1516 is not an entry code for either. However, P1516 and P2135 frequently appear together, and if P2135 is present or in history on a covered vehicle you may qualify. Ask the dealer that specific question.
Will cleaning the throttle body fix P1516?
Only if you also do the idle learn reset afterwards. GM's repair is both steps, and it names the consequence of skipping the second: the concern returns with P0121, P0506 and P0507. If your throttle body was cleaned and the light came back quickly, an incomplete relearn is the most likely reason.
How do I know whether the throttle body needs replacing rather than cleaning?
The GM scan tool parameter "TP Sensor 1 and 2 Agree/Disagree" is the decisive test. Disagree means replace the throttle body. GM also directs replacement if P1516 returns alongside P2101 or P2176 after the cleaning and relearn have been done properly.
Can I drive with P1516?
Cautiously. Electronic throttle faults can produce reduced power modes, and a throttle plate that is not reaching commanded position is not something to leave indefinitely. It is worth diagnosing promptly rather than living with the light.
What does the -00 mean in P1516-00?
No GM-documented sub-types exist for P1516. GM's bulletins write the code bare, so a -00 on your tool is the generic "no sub type information" value rather than a specific GM fault mode.
Bosch or Hitachi — does it matter which throttle body I have?
It matters a lot to the bill. On Hitachi units GM directs fitting the throttle position sensor kit first and replacing the throttle body only if that does not correct the concern. On Bosch units the sensor is not serviced separately. Identify which is fitted before ordering anything.
What torque do the throttle body bolts take?
10 N·m, which is 89 lb in — inch-pounds, not foot-pounds. Over-torquing can distort the housing and create a fresh problem.
Why did P0121, P0506 and P0507 appear after my throttle body was cleaned?
That is GM's documented signature for a missed idle learn reset. The module is still applying its learned compensation for a dirty throttle body to a clean one. Have the idle learn performed through the Tech 2 ECM menu under Module Set Up or Special Functions, TAC System.
Shop the Parts Mentioned
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MOTOPOWER MP69033 OBD2 Scanner — $49, confirms P1516 and graphs live engine data while you test the throttle body.
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VDIAGTOOL BT500 Battery Tester — $57.53, tests battery health, cranking and charging on 6V/12V/24V systems with ripple analysis and a voltage waveform — confirms the battery and charging system are healthy before you chase a sensor or circuit fault.
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ACDelco Gold Negative Battery Cable — useful for addressing related ground and connection issues.
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95-Piece Mechanics Tool Set (Metric & SAE) — for throttle body and ground access.
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3-In-1 Cordless Impact Wrench & Screwdriver Kit — speeds up throttle body removal for cleaning or inspection.