P2008 on 2008-2017 Buick Enclave 3.6L: Intake Manifold Runner Control Circuit Fixes

What's Unique About the 2008-2017 Buick Enclave

The Buick Enclave and its GM Lambda platform siblings (GMC Acadia, Saturn Outlook, Chevrolet Traverse) from this era use a specific solenoid to actuate the intake runners. While many vehicles can suffer from carbon buildup causing stuck flaps, the P2008 code on this platform is more frequently a straightforward electrical failure of the solenoid or its wiring. The solenoid is exposed to significant heat and vibration at the back of the engine, leading to a higher failure rate of the component itself.

Symptoms You May Notice

• Check Engine Light is on
• Reduced engine power and sluggish acceleration, especially below 3,000 RPM
• Rough or unstable idle
• Hesitation when accelerating
• Poor fuel economy
• Engine surging

Most Likely Causes

1. Failed Intake Manifold Runner Control (IMRC) Solenoid/Actuator 🔴 High Probability → Shop Engine Intake Manifold The solenoid is located in an area of high engine heat and vibration, which can cause the internal coil windings to fail and create an open circuit over time. This is the most common failure point for P2008.
   How to confirm: With the engine off, disconnect the solenoid's electrical connector. Use a multimeter to check for resistance across the two pins on the solenoid. An infinite reading (open loop or 'OL') confirms the solenoid has failed internally. You can also perform an active test with a capable scan tool to command the solenoid on and listen for a click. No click indicates a failure in the solenoid or its circuit.
   Typical fix: Replace the IMRC solenoid. It is typically mounted to the intake manifold, often requiring removal of the engine cover and sometimes the throttle body for access.
   Est. part cost: $40-$100
2. Damaged Wiring or Poor Connection 🟡 Medium Probability Wiring near the top and back of the engine is susceptible to heat damage, abrasion, and rodent damage. Connectors can also become loose or corroded. It is very common for the connector to be forgotten or not seated properly after maintenance like spark plug changes.
   How to confirm: Visually inspect the wiring harness leading to the IMRC solenoid for any signs of breaks, chafing, or melting. Unplug the connector and check for corrosion or bent pins. Use a multimeter to check for battery voltage on one pin and ground on the other at the connector with the key on, engine off.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the electrical connector. Secure the harness away from heat sources or sharp edges.
   Est. part cost: $5-$50

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): → Shop Engine Control Module (ECM) This is extremely rare and should only be considered after the solenoid and wiring have been proven to be good. A PCM driver failure can prevent voltage from being sent to the solenoid.

Diagnosis Steps

1. Retrieve the P2008 code and any other codes using an OBD-II scanner.
2. Perform a visual inspection of the IMRC solenoid and its wiring harness, located on the intake manifold. Look for unplugged connectors, broken wires, or signs of heat damage. This is a very common cause, especially after recent service.
3. If a capable scan tool is available, command the IMRC solenoid 'On' and listen for an audible click from the solenoid. No click suggests a problem with the solenoid or its circuit.
4. Disconnect the solenoid's electrical connector. Use a multimeter to test the resistance of the solenoid itself. A reading of 'OL' (Open Line) indicates the solenoid has failed internally and needs replacement.
5. With the key on and engine off, check for voltage at the electrical connector. You should have battery voltage on one wire and a good ground on the other when the PCM commands it. If there is no voltage, inspect the wiring for breaks and check the relevant fuse.
6. If the solenoid tests good and there is voltage at the connector, check for a poor pin fit or corrosion inside the connector that could be causing an intermittent open circuit.
7. If the solenoid and wiring are confirmed to be good, the issue may be with the PCM, but this is highly unlikely.

Parts You'll Likely Need

• Intake Manifold Runner Control Solenoid / Valve (OEM #12616692) — This solenoid is the most common failure point for a P2008 code. Its internal coil fails, creating the 'open circuit' detected by the computer. This part number also replaces the previous number 12590943.
  Trusted brands: ACDelco (GM Genuine), Dorman, Standard Motor Products (SMP), WVE
  OEM price range: $60-$100
  Aftermarket price range: $40-$75

Related Codes That Often Appear With This One

• P2006 — P2006 means 'Intake Manifold Runner Control Stuck Closed'. If the electrical circuit is open (P2008), the solenoid cannot be activated, causing the runners to remain in their default closed position, which then triggers P2006. Fixing the P2008 electrical issue will resolve the P2006 code.

Technical Service Bulletins (TSBs) & Recalls

• While TSBs like 21-NA-149 exist for P2008 on other GM engines due to wiring harness chafing, no specific, widely-cited TSB for this exact issue on the Enclave's LLT V6 was found in the search. Diagnosis should focus on the component and its direct wiring. Other TSBs for this platform relate to timing chains and power steering, which are separate issues.

Platform-Specific Known Issues

• A user on the Edmunds forums with a 2008 Enclave noted a cascade of maintenance issues around 87,000 miles, including power steering components and various sensors, highlighting the potential for multiple repairs on higher-mileage examples.

Mechanic-Grade Diagnostic Values

• IMRC Solenoid Coil Resistance — expected: 8-15 Ohms. Failure: A reading of 'OL' (Open Line / infinite resistance) on a multimeter indicates a failed, open coil. A reading of 0 Ohms would indicate an internal short.
• IMRC Solenoid Connector Voltage (Key On, Engine Off) — expected: One pin should show battery voltage (~12.6V). The other pin is the control wire and will show 0V until the PCM commands it by providing ground.. Failure: No voltage on the power supply pin indicates a blown fuse or a break in the power wire from the fuse block.

Scan Tool Commands That Help

• GM GDS2 (Global Diagnostic System 2): Output Control > Intake Manifold Runner Control Solenoid Command — This bidirectional command allows a technician to manually command the IMRC solenoid on and off while listening for an audible 'click' from the solenoid. This is the fastest way to confirm if the solenoid is receiving the command and is mechanically capable of actuating. If no click is heard, it confirms a fault in the solenoid or its circuit, narrowing down the diagnosis significantly.

Wiring & Ground Locations

• IMRC Solenoid Connector — On the IMRC solenoid itself, mounted to the rear of the intake manifold on the firewall side (Bank 1) for the LLT engine.. This 2-pin connector is a primary failure point. It can be left unplugged after service, become brittle from heat, or its terminals can corrode. The wires right at the back of the connector are also prone to breaking internally from vibration and heat stress.
• G105 — A primary engine-to-chassis ground, often located on the left (driver's side) rear of the engine or on the frame rail.. While the IMRC solenoid is ground-side controlled by the PCM, the PCM itself relies on clean, solid main grounds like G105. A poor main ground can cause erratic behavior and voltage drops across multiple systems, though it's less likely to be the direct cause of a specific open-circuit code like P2008.

Real Owner Repair Stories

• Compilation of multiple forum posts and YouTube videos (2009 GMC Acadia (Lambda Platform Sibling) with 3.6L LLT) — Check Engine Light with code P2008, sluggish performance.
  ❌ Tried (didn't work) Clearing the code (it returned immediately).
  ✅ What actually fixed it Upon inspection, the wiring harness leading to the IMRC solenoid had been chewed through by rodents. The soy-based insulation used on some modern wiring is attractive to pests. The fix involved cutting out the damaged section of wire, splicing in a new piece of wire using weatherproof butt connectors with heat shrink, and wrapping the repaired harness in protective tape treated with a rodent repellent.

OEM Part Supersession History

• 12590943 → 12616692 — Likely an internal revision for durability or manufacturing improvement. This is a common practice for GM parts.
  Heads up: The parts are fully interchangeable. If you have a vehicle that came with 12590943, the correct replacement is 12616692.

Model Year Variations Within This Range

• 2008-2011 (and some early 2012): These models use the LLT 3.6L V6 engine, which has a distinct, externally-mounted IMRC solenoid (PN 12616692) on an aluminum intake manifold. The diagnosis and repair described here primarily apply to this version.
• 2012-2017: These models use the updated LFX 3.6L V6 engine. The LFX features a redesigned composite (plastic) intake manifold with a different, more integrated IMRC actuator design. While a P2008 code can still occur, the part number for the actuator is different and the replacement procedure may vary. The LFX intake also integrates the exhaust manifold into the cylinder head, a completely different architecture from the LLT.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Premature Timing Chain Stretch 🔴 High — Very common on early (2008-2012) LLT engines, often appearing as early as 40,000-80,000 miles. Caused by a combination of chain design and long oil change intervals. (Ref: GM Special Coverage Adjustment #11340C extended warranty coverage to 10 years/120,000 miles for this issue.)
• 3-5-R Transmission Wave Plate Failure 🔴 High — Notorious issue on 2008-2011 models with the 6T70/6T75 transmission, typically occurring around 90,000 miles. Results in loss of 3rd, 5th, and Reverse gears. (Ref: GM Special Coverage Adjustment #14404B extended warranty to 10 years/120,000 miles for the wave plate.)
• Power Steering Failure/Leaks 🟠 Medium — Common across the first generation, causing intermittent loss of power steering assist, especially at low speeds, or fluid leaks from the rack and pinion. (Ref: GM Special Coverage Adjustment #14329B extended warranty coverage for the power steering pump to 10 years/150,000 miles.)
• Stabilitrak / Reduced Engine Power Errors 🟡 Low — Many owners report intermittent 'Service Stabilitrak' and 'Reduced Engine Power' messages, which can be triggered by a wide range of issues, including dirty throttle bodies, faulty wheel speed sensors, or even vacuum leaks.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For the IMRC solenoid/actuator, a used part is a reasonable, budget-conscious choice ONLY if it's from a verified low-mileage donor vehicle. Given the relatively low cost of new aftermarket parts, buying used offers minimal savings for the risk involved.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Check for a clean, undamaged electrical connector port.
• Ensure the plastic housing has no cracks or signs of extreme heat stress.
• If possible, test the resistance with a multimeter before purchase; it should fall within the 8-15 Ohm range.

OEM-only on this vehicle (don't cheap out):

• For this specific P2008 repair, no parts are strictly 'OEM-only'. The solenoid is a simple component well-replicated by the aftermarket.

Aftermarket brands forum-validated for this vehicle:

• Dorman
• Standard Motor Products (SMP)
• WVE (a division of NTK)

Brands owners have reported issues with on this vehicle:

• No-name, unbranded parts from online marketplaces should be avoided, as quality control can be inconsistent.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0008 — Often associated with the LLT engine's known issue of premature timing chain stretch, which may appear alongside other engine performance codes.
• P0017 — Related to timing alignment issues (crankshaft/camshaft correlation) common on early Enclave LLT engines due to chain stretch.
• P0700 — May appear if the vehicle experiences the notorious 3-5-R transmission wave plate failure common on 2008-2011 models.
• P0521 — Related to oil pressure sensor issues which are part of the 'various sensors' mentioned in owner reports for high-mileage 2008 Enclaves.

Frequently Asked Questions