P0307 on 2010-2013 GMC Yukon Denali: Cylinder 7 Misfire Causes and Fixes

What's Unique About the 2010-2013 Gmc YUKON DENALI

The 2010-2013 Yukon Denali is equipped with a 6.2L V8 (L94) engine that features Active Fuel Management (AFM). This system is designed to improve fuel economy by deactivating cylinders 1, 4, 6, and 7 under light loads. The special hydraulic lifters used for these AFM cylinders are a notorious failure point. They can become mechanically stuck or hydraulically collapse, preventing the valve from opening. Since cylinder 7 is one of the AFM cylinders, a P0307 code is a strong indicator of this specific mechanical failure, which is more complex and costly than a standard ignition or fuel problem.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Flashing or solid Check Engine Light
• Engine ticking or tapping noise, which can intensify with acceleration and strongly indicates a lifter issue.
• Exhaust smells rich with unburned fuel.
• Service StabiliTrak warning message may appear alongside the check engine light.

Most Likely Causes

1. Failed Spark Plug 🔴 High Probability → Shop Spark Plug
   How to confirm: Remove the spark plug from cylinder 7 (rear-most on the driver's side) and inspect it for wear, fouling, or damage. A definitive test is to swap it with a plug from another cylinder (e.g., cylinder 1), clear the codes, and see if the misfire code changes to P0301.
   Typical fix: Replace the spark plug. It is recommended to replace all 8 spark plugs at the same time using the specified OEM part (e.g., ACDelco Iridium).
   Est. part cost: $10-$20 per plug
2. Failed Ignition Coil 🔴 High Probability → Shop Ignition Coil
   How to confirm: Swap the ignition coil from cylinder 7 with another cylinder (e.g., cylinder 1). Clear the codes and run the engine. If the code changes to P0301, the ignition coil is faulty. This is a common and highly recommended first diagnostic step.
   Typical fix: Replace the faulty ignition coil. It is a simple, single-bolt replacement.
   Est. part cost: $55-$110
3. Loose or Failed Spark Plug Wire 🔴 High Probability → Shop Spark Plug A GM Technical Service Bulletin (TSB #PIP4819A) specifically calls out inspecting and replacing loose spark plug wires as a primary fix for misfire codes on these models.
   How to confirm: Visually inspect the spark plug wire for cylinder 7 for any signs of damage, burns, or a loose connection at the coil or spark plug. Ensure it is securely clicked into place on both ends. 🎬 Watch: How to quickly diagnose a loose spark plug wire. Wiggle the wire to check for a secure fit. A resistance test should show less than 30,000 ohms.
   Typical fix: Replace the spark plug wire. It is best practice to replace the entire set of 8 wires.
   Est. part cost: $60-$190 for a set
4. Collapsed or Stuck AFM Lifter 🟡 Medium Probability → Shop Engine Valve Lifter The AFM system deactivates cylinders 1, 4, 6, and 7. The special lifters used for this system are a known weak point and can fail, causing a persistent misfire on the affected cylinder. This is a widely documented issue in owner forums for the Yukon, Escalade, and Silverado.
   How to confirm: After ruling out ignition and fuel issues, a distinct ticking/tapping noise from the driver's side of the engine is a strong indicator. The definitive test is to remove the driver's side valve cover and start the engine briefly. Visually confirm that the rocker arms for cylinder 7 are not moving, 🎬 See how to confirm a collapsed lifter under the valve cover. or have significantly less travel, compared to other cylinders. This indicates the lifter has collapsed and is not actuating the pushrod. A compression test will also show very low or zero compression on cylinder 7.
   Typical fix: This is a major repair. It requires removing the cylinder head to replace the faulty lifter(s). 🎬 Watch: Step-by-step guide to removing the head and replacing lifters. Due to the high failure rate, many owners and shops recommend an 'AFM Delete,' which involves replacing all 16 lifters with standard (non-AFM) LS7-style lifters, replacing the camshaft with a non-AFM profile cam, replacing the VLOM (Valve Lifter Oil Manifold) with a standard valley cover, and reprogramming the ECU to disable the AFM system.
   Est. part cost: $300-$800 for lifters and gaskets; $1500-$2500+ for a full AFM delete kit including a new camshaft.
5. Clogged or Failed Fuel Injector ⚪ Low Probability → Shop Fuel Injector Debris or rust from the fuel system can clog the injector's inlet screen.
   How to confirm: Listen to the injector with a mechanic's stethoscope to confirm it is clicking. Use a 'noid' light to verify the electrical connector is receiving a pulse. Swapping the injector with another cylinder is a definitive but more labor-intensive test. A resistance test should yield a reading between 11 and 14 ohms for the L94's Flex Fuel injectors.
   Typical fix: Replace the faulty fuel injector. It is recommended to replace the O-rings on adjacent injectors when the fuel rail is removed.
   Est. part cost: $80-$150

Rare But Worth Checking

• Low Engine Compression: Beyond a failed lifter, this could be caused by worn piston rings, a damaged piston, or a problem with the cylinder head valves (e.g., bent valve, dropped valve seat). A compression test followed by a cylinder leak-down test is required for diagnosis.
• Intake Manifold Gasket Leak: → Shop Engine Intake Manifold A vacuum leak from a failed intake manifold gasket near the cylinder 7 runner can lean out the air/fuel mixture and cause a misfire. This can be diagnosed with a smoke test or by spraying carb cleaner near the gasket and listening for an engine RPM change.
• VLOM (Valve Lifter Oil Manifold) Failure: The VLOM controls oil flow to the AFM lifters. A failure in the solenoid or passages for cylinder 7 can lead to lifter collapse. If replacing AFM lifters, it's often recommended to replace the VLOM as well.

Diagnosis Steps

1. Use an OBD-II scanner to confirm P0307 and check for any other codes, especially P0300.
2. Inspect the spark plug wire for cylinder 7 (rear-most on the driver's side) for damage or loose connections, as noted in TSB #PIP4819A.
3. Swap the ignition coil from cylinder 7 with cylinder 1. Clear codes, run the engine, and see if the misfire moves to P0301. If it does, the coil is bad.
4. If the misfire remains on cylinder 7, swap the spark plug from cylinder 7 with cylinder 1. If the code changes to P0301, the spark plug is bad.
5. If ignition components are good, listen for a steady clicking sound from the cylinder 7 fuel injector with a stethoscope. Use a noid light to confirm it's receiving an electrical signal.
6. Listen for a distinct ticking/tapping noise from the driver's side valve cover area. If present, this strongly points to a failed AFM lifter.
7. Perform a compression test on cylinder 7. Very low or zero compression strongly suggests a mechanical issue, most likely a collapsed AFM lifter.
8. For definitive confirmation of a collapsed lifter, remove the driver's side valve cover. Start the engine briefly and observe the rocker arms for cylinder 7. If one or both are stationary or barely moving, the corresponding lifter has failed.

Parts You'll Likely Need

• Ignition Coil (OEM #12611424 (Superseded by D510C)) — A common failure point for ignition systems. Easy to diagnose by swapping with another cylinder.
  Trusted brands: ACDelco, Delphi
  OEM price range: $80-$110
  Aftermarket price range: $55-$80
• Spark Plug Wire Set (OEM #ACDelco 9748RR) — Cited in a TSB as a potential cause for this exact issue. Wires can degrade over time or become loose. [Bulletin #PIP4819A]
  Trusted brands: ACDelco, NGK
  OEM price range: $90-$150
  Aftermarket price range: $60-$100
• Spark Plugs (OEM #ACDelco 41-162 (Iridium)) — Spark plugs are a routine maintenance item and a primary cause of misfires when worn or fouled.
  Trusted brands: ACDelco, NGK
  OEM price range: $10-$15 per plug
  Aftermarket price range: $5-$10 per plug
• Active Fuel Management (AFM) Lifter (OEM #12648846 (Note: This is also the standard lifter part number; AFM lifters are visually distinct)) — A well-documented failure point on this engine platform that directly causes misfires on AFM cylinders (1, 4, 6, 7).

Related Codes That Often Appear With This One

• P0300 — If the misfire is intermittent or severe enough to affect engine balance, the PCM may also log a P0300 (Random/Multiple Cylinder Misfire Detected) code alongside the specific P0307.
• C0242, C0561 — The engine misfire can cause erratic crankshaft position sensor readings, which can sometimes trigger diagnostic trouble codes for the traction control or StabiliTrak system, often accompanied by a 'Service StabiliTrak' message on the dash.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIP4819A: Dated 2013-02-05, this TSB addresses engine misfires (P0300-P0308) and instructs technicians to inspect for and replace loose-fitting spark plug wires as a potential cause.

Platform-Specific Known Issues

• Active Fuel Management (AFM) Lifter Failure: The most significant issue for this platform. The 6.2L V8 engine uses AFM to deactivate cylinders 1, 4, 6, and 7 under light load. The specialized lifters for these cylinders are prone to failure, where they can become stuck or collapse. This prevents the valve from opening, causing a complete lack of compression and a persistent P0307 misfire. This repair is labor-intensive and often requires camshaft inspection or replacement if the failed lifter's roller has damaged a cam lobe. Many owners opt for a permanent 'AFM Delete' to prevent future failures.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Resistance — expected: 0.500 ohms. Failure: Significant deviation from the expected value.
• Ignition Coil Secondary Resistance — expected: 2.00K ohms. Failure: Significant deviation from the expected value.
• Spark Plug Wire Resistance — expected: 4,000-20,000 ohms. Failure: A reading above 30,000 ohms indicates a bad wire.
• Fuel Injector Resistance (Flex Fuel L94) — expected: 11 to 14 ohms. Failure: Readings outside this range suggest a faulty injector coil.
• Engine Oil Pressure (Hot Idle) — expected: 25-30 PSI. Failure: Pressure significantly below this range can cause AFM lifter actuation problems, leading to misfires.

Scan Tool Commands That Help

• GDS2 / Tech2: Cylinder Power Balance Test / Misfire Graphic — Use this function to view live misfire counts for each cylinder. This helps confirm that cylinder 7 is the only cylinder misfiring and verifies if a repair (like swapping a coil) has moved the misfire to a different cylinder.
• GDS2 / Tech2: AFM Solenoid Control — A technician can command specific AFM solenoids on and off to test the electrical side of the system. If commanding the cylinder 7 solenoid doesn't change engine behavior or if the misfire persists after lifter replacement, it can point to a faulty VLOM or wiring.

Wiring & Ground Locations

• G102 — Located at the left rear of the engine.. This ground point is specifically for the 8 ignition coils. A poor connection here can cause weak or intermittent spark on one or more cylinders, leading to misfire codes.
• G103 — Located on the front of the right-side (passenger side) cylinder head.. This is a primary engine-to-chassis ground. While not specific to one component, a poor connection here can cause a host of electrical issues, including problems with the ECM and sensor readings that could contribute to misfire detection.
• G104 — Located on the rear of the left-side (driver side) cylinder head.. This is another critical engine ground. Given its proximity to cylinder 7 (rear driver's side), checking its integrity is a wise step when diagnosing any issue on that side of the engine.

Real Owner Repair Stories

• YouTube user 87SSBoi (2007 Chevrolet Tahoe (GMT900 platform with similar AFM engine)) — Shaking engine, P0307 misfire code.
  ❌ Tried (didn't work) Replaced spark plug on cylinder 7, Replaced spark plug wire on cylinder 7, Replaced ignition coil on cylinder 7
  ✅ What actually fixed it The misfire remained after all ignition parts were replaced. Further diagnosis revealed a collapsed AFM lifter on cylinder 7. The final fix was a mechanical repair of the lifter and an AFM delete reprogramming.
• YouTube user Just an Average Joe (GMC Sierra 5.3L (similar AFM system)) — Engine running rough, P0307 misfire code.
  ❌ Tried (didn't work) Initial diagnosis pointed away from ignition after basic checks.
  ✅ What actually fixed it The mechanic confirmed a collapsed AFM lifter on the intake valve for cylinder 7. The video shows the failed lifter compared to a new one. The fix was to pull the cylinder head and replace the lifter.
• Reddit user zeus99es (Chevrolet Tahoe (GMT900 platform)) — P0307 code, random rough idle.
  ❌ Tried (didn't work) N/A - owner suspected AFM issue immediately.
  ✅ What actually fixed it The owner cleared the code and began driving in Manual mode (M5) to prevent the AFM system from activating. They also ordered a plug-in AFM disabler device. Keeping the AFM system from engaging prevented the code and rough idle from returning, serving as a workaround to avoid immediate mechanical repair.

When the Usual Fixes Don't Work

• In some rare cases, replacing the collapsed AFM lifter(s) on cylinder 7 may not fix the misfire. One owner on a forum reported replacing all 8 AFM lifters for a P0307, only to have the misfire on cylinder 7 return immediately. When observing the engine with the valve cover off, the new lifters for cylinder 7 were still not actuating. This points the diagnosis away from the lifter itself and towards the components that control it: a faulty VLOM (Valve Lifter Oil Manifold) not sending oil pressure to the lifter correctly, or an electrical issue with the solenoid for that cylinder.

OEM Part Supersession History

• 12570616 → 12611424 — Standard part evolution and supplier changes.
  Heads up: ACDelco's professional service part number for 12611424 is D510C. These numbers are interchangeable.

Model Year Variations Within This Range

• 2010-2013: The 6.2L V8 in the 2010-2013 Yukon Denali is the L94 variant. Its key difference from the preceding L9H (2009) and L92 (2007-2008) engines was the addition of Active Fuel Management (AFM). This is the specific system responsible for the high rate of lifter failures on cylinders 1, 4, 6, and 7, making P0307 a much more common and mechanically-involved code on these model years.