P0351 on GMC Terrain
Factory diagnostic protocol and troubleshooting wire for fault code P0351 specifically for the GMC Terrain (2020–2026, 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages).
1. Symptoms of P0351 on GMC Terrain
When the Engine Control Module (ECM/PCM) on your GMC Terrain (1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages) logs fault code P0351, drivers commonly observe:
2. Most Likely Causes on GMC Terrain
Historical warranty claims and technical repair bulletins for GMC Terrain point to the following failure distribution:
3. Step-by-Step DIY Repair Guide for GMC Terrain
Identify Cylinder 1 ignition coil pack mounted on the valve cover. on the GMC Terrain equipped with 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages.
Swap Coil 1 with Coil 2. Clear codes and restart engine. If code switches to P0352 (Coil B), the ignition coil is 100% defective. on the GMC Terrain equipped with 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages.
Check for 12V battery power, chassis ground, and 5V trigger pulse from the PCM on the 3-pin / 4-pin harness plug. on the GMC Terrain equipped with 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages.
Install a new OEM ignition coil (e.g. Denso, Motorcraft, Delphi) and replace the spark plug on Cylinder 1. on the GMC Terrain equipped with 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages.
Clear DTCs and verify smooth acceleration under load. on the GMC Terrain equipped with 1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages.
Equipment for Diagnosing GMC Terrain (P0351)
Direct-Fit Laser Iridium Spark Plugs (Set of 4/6)
Pre-gapped iridium spark plugs engineered to restore smooth combustion on GMC Terrain.
Magnetic Swivel Spark Plug Socket Set
360-degree magnetic swivel socket prevents ceramic plug cracks inside deep engine spark wells.
BlueDriver Bluetooth Pro OBDII Scan Tool
Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.
Other Common Fault Codes on GMC Terrain
Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the GMC Terrain:
4. GMC Terrain P0351 FAQs
What causes code P0351 to trigger on a GMC Terrain?
On the GMC Terrain (1.5L Turbo 4-Cyl (175HP) / Denali & AT4 Trim Packages), P0351 is most frequently caused by Failed ignition coil pack on Cylinder 1 (Coil A) or Broken or melted wiring harness to ignition coil 1.
Where is the OBD-II port located on my GMC Terrain?
On the GMC Terrain, the 16-pin DLC diagnostic connector is located Driver footwell directly above brake pedal. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.
Can I safely drive my GMC Terrain with code P0351?
No. Cylinder 1 ignition coil has failed completely, causing an active misfire and dumping unburned fuel into the catalytic converter. Given that P0351 carries a Critical severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.