P0272 on 2016-2019 GMC Sierra 1500: Cylinder 4 Contribution Fault Causes and Fixes

What's Unique About the 2016-2019 Gmc SIERRA 1500

On the EcoTec3 engines in this generation of Sierra, a P0272 code can range from a simple fix to a sign of a more complex problem. While a faulty fuel injector is the most frequent culprit, these engines are known for issues with the Active Fuel Management (AFM) system. A collapsed or stuck AFM lifter can cause a persistent ticking noise and trigger cylinder contribution codes like P0272. GM has issued Technical Service Bulletins (TSBs) that point to this possibility, making a thorough diagnosis that includes listening for valvetrain noise crucial before assuming it's just a fuel or spark issue.

Diagnostic Flowchart

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

Generation note: The 2016-2019 year range covers two distinct generations. The 2016-2018 models and the 2019 'Sierra 1500 Limited' are on the K2XX platform. The all-new 2019 Sierra 1500 is on the T1XX platform. While the primary causes for P0272 (injector, coil, plug) are similar across both, engine and electronic systems differ, so be sure to source the correct parts for your specific 2019 model. The underlying AFM lifter issue is prevalent in V8s across both platforms.

Symptoms You May Notice

• Rough or vibrating engine idle
• Noticeable loss of power and poor acceleration
• Engine hesitation or stumbling
• Flashing or solid Check Engine Light
• Reduced fuel economy
• Engine ticking or chirping noise, especially when cold or at idle

Most Likely Causes

1. Faulty Fuel Injector (Cylinder 4) 🔴 High Probability → Shop Fuel Injector Direct injection systems operate under high pressure, and injectors can become clogged with carbon deposits or fail electronically over time, leading to poor atomization or incorrect fuel delivery.
   How to confirm: Swap the fuel injector from cylinder 4 with one from another cylinder (e.g., cylinder 2). Clear the codes and drive the vehicle. If the trouble code changes to P0266 (Cylinder 2 Contribution/Balance), the injector is faulty.
   Typical fix: Replace the cylinder 4 fuel injector and its seals. 🎬 Watch: Step-by-step guide to replacing the fuel injectors on this engine.
   Est. part cost: $50-$150
2. Faulty Ignition Coil (Cylinder 4) 🟡 Medium Probability → Shop Ignition Coil
   How to confirm: Swap the ignition coil from cylinder 4 with one from another cylinder (e.g., cylinder 2). If the code changes to P0266, the ignition coil is bad. This is a common and easy diagnostic step.
   Typical fix: Replace the cylinder 4 ignition coil.
   Est. part cost: $30-$75
3. Worn or Fouled Spark Plug (Cylinder 4) 🟡 Medium Probability → Shop Spark Plug
   How to confirm: Remove and inspect the spark plug from cylinder 4. Look for excessive wear, oil fouling, carbon buildup, or damage to the electrode or insulator. Compare it to a plug from a healthy cylinder.
   Typical fix: Replace the spark plug. It's often recommended to replace all spark plugs at the same time for consistent performance.
   Est. part cost: $10-$25

Rare But Worth Checking

• Collapsed or Stuck AFM Lifter: → Shop Engine Valve Lifter A major known issue on these GM V8s. The Active Fuel Management (AFM) lifters can fail, getting stuck in a collapsed state. This results in the valves for that cylinder not opening correctly, causing a complete loss of contribution and often a distinct ticking or clacking sound. TSB #PIP-5400 references this as a lack of valvetrain lubrication leading to cylinder imbalance codes. This is a serious mechanical failure requiring cylinder head removal to fix.
🎬 See how to diagnose and replace a collapsed AFM lifter.
• Wiring Harness Issue: A damaged wire or corroded connector for the cylinder 4 fuel injector or ignition coil can cause an intermittent signal and trigger the code. The injector harness can chafe against engine components, leading to a short or open circuit. A visual inspection of the harness leading to the cylinder 4 components is recommended.
• Engine Control Module (ECM) Anomaly: → Shop Engine Control Module (ECM) TSB #17-NA-171 suggests that an anomaly within the ECM itself can cause this code, sometimes alongside other cylinder contribution codes. This may require a software update or ECM replacement by a dealer.
• Internal Engine Mechanical Failure: Besides a lifter, low compression in cylinder 4 due to worn piston rings, a bad valve, or a head gasket leak can trigger this code. A compression test is needed to diagnose this after fuel and spark causes are ruled out.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner and note any accompanying codes like P0304 or P0300.
2. Listen carefully to the engine at idle for any ticking or metallic tapping sounds. A distinct tick can point directly to a valvetrain/lifter issue.
3. For V8 engines, locate cylinder 4. It is the second cylinder from the front on the passenger side.
4. Inspect the spark plug in cylinder 4 for wear, damage, or fouling. Replace if necessary.
5. Swap the ignition coil from cylinder 4 with the coil from cylinder 2. Clear the codes and drive the vehicle. If the code changes to P0266 (Cylinder 2 Contribution/Balance), the coil is faulty.
6. If the code remains P0272, swap the fuel injector from cylinder 4 with the injector from cylinder 2. Clear codes and drive. If the code changes to P0266, the injector is faulty.
7. If the problem still persists on cylinder 4, inspect the wiring and connector for the cylinder 4 injector and coil for any signs of damage, corrosion, or chafing.
8. If wiring is intact and no ticking was heard, perform a compression test to check for mechanical engine problems (piston rings, valves, head gasket).
9. If a persistent ticking noise is present and other steps don't resolve the issue, the cause is very likely a failed AFM lifter. This requires professional diagnosis and repair.
10. If all other diagnostics fail, consult the TSBs regarding potential ECM issues.

Parts You'll Likely Need

• Fuel Injector (OEM #12668390) — This is the most common cause of a P0272 code on these trucks when a mechanical fault is not present.
  Trusted brands: ACDelco, Bosch
  OEM price range: $90-$170
  Aftermarket price range: $50-$100
• Ignition Coil (OEM #12611424 / D521C) — A common failure point that can cause cylinder-specific performance issues. The ACDelco D521C is a widely used replacement.
  Trusted brands: ACDelco, NGK, Delphi
  OEM price range: $50-$90
  Aftermarket price range: $30-$75
• Spark Plug (OEM #41-123) — A basic maintenance item that is a frequent cause of ignition and performance problems. The ACDelco 41-123 is a common OEM Iridium plug for these engines.
  Trusted brands: ACDelco, NGK
  OEM price range: $15-$25
  Aftermarket price range: $8-$15

Related Codes That Often Appear With This One

• P0304 — This code indicates 'Cylinder 4 Misfire Detected'. P0272 is a balance/contribution fault, while P0304 is a specific misfire event. 🎬 Watch: Diagnosing the engine tick and misfire codes on a Sierra. They often appear together because a cylinder that isn't contributing properly is also likely to be misfiring.
• P0300 — This code for 'Random/Multiple Cylinder Misfire' can appear if the underlying issue, such as a failing AFM lifter, begins to affect overall engine stability or if multiple lifters are failing.
• P0263, P0266, P0269, etc. — These are the contribution/balance fault codes for other cylinders. Seeing multiple codes like this together could point to a widespread issue like a fuel delivery problem, a major vacuum leak, or the ECM anomaly mentioned in TSB #17-NA-171.

Technical Service Bulletins (TSBs) & Recalls

• PIP5468F: Mentions P0272 in a long list of potential engine-related DTCs, advising technicians to follow standard service diagnostics.
• 17-NA-171: Identifies a possible ECM anomaly as a cause for P0272 and other codes.
• PIP-5400: Links P0272 and other cylinder balance codes to a potential lack of lubrication in the valvetrain, a symptom related to AFM lifter issues.

Platform-Specific Known Issues

• TSB #PIP-5400 notes that P0272 can be associated with a lack of lubrication to valvetrain components, which is a significant mechanical concern often pointing to AFM lifter failure.
• TSB #17-NA-171 indicates that an anomaly in the Engine Control Module (ECM) could be the cause, requiring dealer-level diagnostics and potentially reprogramming.
• Active Fuel Management (AFM) Lifter Failure: This is the most significant vehicle-specific issue. A collapsed lifter on cylinder 4 will cause P0272 and P0304, accompanied by a ticking noise. This is a well-documented problem across GM's V8 truck and SUV lineup from this era.

Mechanic-Grade Diagnostic Values

• Fuel Injector Resistance — expected: 12-17 Ohms for most gasoline engines. Some sources cite 13.5 Ohms specifically for 5.3L engines.. Failure: A reading significantly outside this range indicates a faulty injector coil.
• GDS2 Injector Balance Test Pressure Drop — expected: Pressure drop values for each cylinder should be within 20% of the average of all cylinders.. Failure: If cylinder 4's pressure drop is more than 20% different from the average of the other cylinders, it indicates a flow issue (clogged or leaking).

Scan Tool Commands That Help

• GDS2 (GM Techline Connect): Automated Injector Balance Test — This is a key diagnostic step after ruling out spark issues. The tool commands the ECM to pulse each injector individually while monitoring the fuel rail pressure drop. This can definitively identify a clogged or under-performing injector without physically removing it.
• GDS2 (GM Techline Connect): Cylinder Power Balance — This function allows a technician to disable one cylinder at a time to observe the corresponding drop in engine RPM. If disabling cylinder 4 causes little or no change in RPM compared to other cylinders, it confirms cylinder 4 is not contributing properly.

Wiring & Ground Locations

• G103 / G104 — G103 is on the front of the passenger side cylinder head. G104 is on the rear of the passenger side cylinder head.. These are primary engine ground points. A loose or corroded connection at these locations can cause erratic behavior in sensors, the ECM, and injector/coil drivers, potentially leading to false contribution fault codes.
• Cylinder 4 Injector Connector — On the passenger side of the engine, second injector from the front. The power wire is typically pink on GM harnesses, with the other wire being the ground pulse signal from the ECM.. The connector itself or the wiring leading to it can become damaged from heat and vibration, causing an open or short in the injector circuit. This is a common point of failure.

Real Owner Repair Stories

• YouTube Channel 'Gabriel Reese Mobile Mechanic' (Chevy Silverado 5.3L (similar platform and engine)) — Engine misfire and ticking noise.
  ❌ Tried (didn't work) Initial diagnosis pointed towards a common misfire, but the persistent ticking noise was the key symptom.
  ✅ What actually fixed it The root cause was a collapsed AFM/DOD lifter. The repair involved removing the passenger side cylinder head to access and replace the failed lifter and lifter guide. The mechanic noted that it's best practice to replace all lifters on that bank at the same time.
• YouTube Channel 'Rainman Ray's Repairs' (GMC Sierra with Duramax Diesel (different engine, but relevant to connector failure)) — Check engine light with P0204 (Injector Circuit/Open Cylinder 4) and P0304 (Cylinder 4 Misfire), causing a sputter and miss.
  ❌ Tried (didn't work) The owner initially suspected bad fuel.
  ✅ What actually fixed it The plastic connector for the cylinder 4 fuel injector was faulty. Replacing the injector pigtail/connector resolved the issue. This highlights that the wiring and connector should be inspected closely, not just the injector itself.

OEM Part Supersession History

• 12668390 → 12681212, and potentially others like 12710481 in kits. — Standard part evolution for reliability or manufacturing improvements.
  Heads up: Injectors for the 2014-2018 K2XX platform (including the 2019 'Limited') are NOT compatible with the redesigned 2019+ T1XX platform trucks due to changes in fuel rails and electronics.

Model Year Variations Within This Range

• 2019: In 2019, GMC sold both the old K2XX platform as the 'Sierra 1500 Limited' and the new T1XX platform as the 'Sierra 1500'. The 'Limited' is effectively a 2018 model and uses parts from that generation. The new T1XX model introduced new engine options (like a 2.7L Turbo and 3.0L Diesel) and updated V8s with Dynamic Fuel Management (DFM) instead of AFM, along with different electronics and part numbers.