GMC Terrain & Acadia Code P1516: Meaning, Causes & How to Fix It

Straight answer first, because it affects half the people reading this page: we could not find a single GM document covering P1516 on the GMC Terrain, in any model year. The Acadia is a different story — GM has written a bulletin about P1516 on the 2007–2011 Acadia 3.6L, and the root cause it identifies is not the throttle body at all. It's the PCV system.

The Terrain Question

We searched GM's bulletin archive for P1516 across every GMC platform and opened every candidate document. No GM bulletin, preliminary information document, special coverage or recall covers P1516 on the GMC Terrain.

That does not prove a Terrain cannot set the code — GM Service Information is paywalled, and a code can exist in a module's software without ever being the subject of a field bulletin. But it does mean nobody should be telling you what P1516 "means on a Terrain" with confidence, and the pages that do are extrapolating from other vehicles.

If you have a Terrain with P1516, the general throttle actuator guidance on our Chevrolet P1516 page is the closest documented material, since it covers the same GM throttle system. Read it knowing it was written for other platforms.

The Acadia: What GM Actually Documents

GM document PI0746A covers P1516 on the 2007–2011 GMC Acadia with the 3.6L V6, in both LY7 and LLT forms. What makes it worth reading is that the fault it describes isn't a dirty throttle body in the ordinary sense.

GM attributes the condition to ice and oil deposits forming at the base of the throttle body — and identifies the root cause as the PCV system. Crankcase vapour carrying oil mist reaches the throttle body, and in cold conditions the moisture in it freezes there. The throttle plate is then physically obstructed, the commanded angle isn't achieved, and P1516 sets.

The practical consequence is significant: cleaning the throttle body treats the symptom. If the PCV system is why the deposits are forming, the deposits come back. That is why GM's labor times for this repair are measured in hours rather than the usual throttle-body-clean figure — 4.6 hours on the LLT and 3.2 hours on the LY7.

Special Coverage — and Its Real Entry Code

There is a genuine GM programme here, and it is worth knowing about, but the way it is usually described online is wrong.

Special Coverage 14582 covers the 2009–2012 GMC Acadia and 2008–2012 GMC Canyon (along with a list of Chevrolet, Buick and Cadillac vehicles) for 10 years or 120,000 miles from the in-service date, regardless of ownership, at no charge.

But we opened the document, and the entry criterion is DTC P2135, P0121 or P0221 — not P1516. GM states that where the qualifying code is absent, the repairs are not covered.

So the useful question to put to a dealer is not "is P1516 covered." It is: "is P2135, P0121 or P0221 present or in history on this VIN?" Those codes come from the same throttle system and frequently accompany P1516, so it is genuinely worth checking — but that is the question that decides who pays.

The Two-Part Code Form: P1516-XX

No GM-documented sub-types were found for P1516. Every GM document naming this code writes it bare, with no failure type byte. The 32-row tables published elsewhere, running -00 through -1F, are auto-generated boilerplate applied to every code on those sites and carry no manufacturer attribution.

How It's Diagnosed on an Acadia

A Tech 2 or a scan tool with equivalent GM function access is required, because two of the steps that matter exist only there: the throttle position sensor agreement parameter, and the idle learn reset that completes any throttle body service.

1. Read all codes and note whether P2135, P0121 or P0221 is present — that is the special coverage question, and it is worth answering before anyone starts billing.
2. Check the "TP Sensor 1 and 2 Agree/Disagree" parameter. Disagree points at the throttle body itself.
3. Remove the intake duct and inspect the base of the throttle body specifically for oil deposits and, in cold weather, ice. That pattern is the PI0746A signature.
4. Investigate the PCV system if oil deposits are found. Cleaning without addressing why oil is arriving there is a repeat visit.
5. After any throttle body cleaning, perform the idle learn reset through the Tech 2 ECM menu under Module Set Up or Special Functions, TAC System. Skipping it brings the concern back with P0121, P0506 and P0507.
6. Torque throttle body fasteners to 10 N·m (89 lb in) — inch-pounds.

Parts, Labor Time and Cost

Note the gap between those two repairs. The special coverage operations are one to one-and-a-third hours. The PCV-related repair GM documents for the 3.6L Acadia is three to nearly five hours. They are different jobs addressing different root causes, and only one of them is potentially free.

An ordering rule worth knowing: on vehicles fitted 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 is fitted before ordering.

GM Documents That Name P1516

No GM document covers P1516 on the GMC Terrain, and no NHTSA recall relates to this code on the models we checked.

Frequently Asked Questions

Does P1516 affect the GMC Terrain?

No GM bulletin, preliminary information document, special coverage or recall covers P1516 on the Terrain in any model year, and we opened every candidate document to check. That is not proof the code cannot set — GM Service Information is paywalled — but any page telling you what P1516 means specifically on a Terrain is extrapolating rather than citing GM.

What causes P1516 on a GMC Acadia?

GM document PI0746A attributes it on the 2007–2011 Acadia 3.6L to ice and oil deposits forming at the base of the throttle body, with the root cause identified as the PCV system. Crankcase vapour carries oil mist to the throttle body, and moisture in it freezes there in cold conditions, physically obstructing the plate.

Is P1516 covered by GM's special coverage on my Acadia?

Not on the strength of P1516 alone. Special Coverage 14582 covers the 2009–2012 Acadia for 10 years or 120,000 miles regardless of ownership, but its entry criterion is DTC P2135, P0121 or P0221. Ask your dealer whether any of those three is present or in history — that, not P1516, decides eligibility.

Will cleaning the throttle body fix it on an Acadia?

It may clear the code, but if the PCV system is why the deposits formed, they will form again. That is why GM's labor time for this repair is 4.6 hours on the LLT and 3.2 on the LY7 rather than a simple cleaning figure — the documented repair addresses more than the throttle body surface.

What happens if the idle learn reset is skipped?

GM names the outcome: the concern returns with P0121, P0506 and P0507. After any throttle body service the idle learn must be performed through the Tech 2 ECM menu under Module Set Up or Special Functions, TAC System.

What does the -00 mean in P1516-00?

No GM-documented sub-types exist for P1516. GM writes the code bare in every document naming it, so a -00 is the generic "no sub type information" value.

How much should an Acadia P1516 repair cost?

It depends which repair applies. The special coverage operations are 1.0 to 1.3 hours and potentially free if a qualifying code is present. The PCV-related repair GM documents for the 3.6L is 3.2 to 4.6 hours plus five part numbers, and is not covered by that programme.

What torque do the throttle body fasteners take?

10 N·m, which is 89 lb in — inch-pounds, not foot-pounds. Over-torquing distorts the housing.

Shop the Parts Mentioned

• MOTOPOWER MP69033 OBD2 Scanner — $49, confirms P1516 and monitors throttle position live. A throttle relearn is a bidirectional procedure this reader does not perform.
• 95-Piece Mechanics Tool Set (Metric & SAE) — for throttle body removal and cleaning.
• 3-In-1 Cordless Impact Wrench & Screwdriver Kit — speeds up throttle body access.
• ACDelco Gold Negative Battery Cable — addresses related ground and connection issues.