Corroded, loose, or broken ground strap between the engine block and chassis; Faulty ignition coil or ignition control module ground wire; Damaged wiring harness or connector at the ignition ground circuit; Poor connection at the battery negative terminal or engine ground point; Failed ignition control module or coil pack internal ground; Corrosion or damage at the PCM ground connection

DTC codes / GM codes / P1376

P1376 · GMIgnition Ground Circuit

Q: What does code P1376 mean?

Ignition Ground Circuit. P1376 on GM vehicles indicates that the powertrain control module has detected a problem with the ignition system's ground circuit, which provides the return path for the ignition coils or ignition control module. The computer monitors this circuit and sets the code when the ground path shows excessive resistance or an open circuit, potentially causing misfires or a no-start condition.

P1376 on GM vehicles indicates that the powertrain control module has detected a problem with the ignition system's ground circuit, which provides the return path for the ignition coils or ignition control module. The computer monitors this circuit and sets the code when the ground path shows excessive resistance or an open circuit, potentially causing misfires or a no-start condition.

SystemPowertrain

Code typeGM specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Engine may misfire or run rough, especially under load
Intermittent stalling or a no-start condition
Check Engine Light illuminated, often with no other noticeable symptoms
Reduced engine power or poor acceleration
Backfiring or popping from the exhaust

Common causes, most likely first

Corroded, loose, or broken ground strap between the engine block and chassis
Faulty ignition coil or ignition control module ground wire
Damaged wiring harness or connector at the ignition ground circuit
Poor connection at the battery negative terminal or engine ground point
Failed ignition control module or coil pack internal ground
Corrosion or damage at the PCM ground connection

How to diagnose and fix it

Inspect and clean the battery negative terminal and engine ground connections
Check the ground strap between the engine block and firewall/chassis for corrosion or breaks
Test the ignition ground circuit for continuity and excessive resistance using a multimeter
Inspect the ignition coil and ignition control module connectors for loose pins or corrosion
Repair or replace any damaged ground wires or connectors in the ignition circuit
Clear the code and test-drive the vehicle to verify the repair

Ground Circuit Faults That Mimic Ignition Failures

A poor engine ground can cause the ignition system to find a return path through other components, leading to mysterious electrical gremlins and multiple unrelated codes.
Many technicians replace ignition coils or modules unnecessarily when the real issue is a corroded ground strap hidden behind the engine or under the battery tray.
P1376 can be set intermittently by a ground connection that only fails under vibration or temperature changes, so a wiggle test of the harness and grounds is essential.
The ignition ground circuit often shares a ground point with other sensors or modules, so a single bad ground can trigger several codes simultaneously.
On some GM vehicles, the ignition ground is routed through a splice pack that can corrode internally, requiring disassembly and cleaning rather than simple wire replacement.

Can I keep driving with P1376?

If the vehicle is running without noticeable misfires, you can drive cautiously to a repair shop, but avoid heavy acceleration or long trips. If the engine is misfiring badly, stalling, or won't start, stop driving and have the vehicle towed to prevent damage to the catalytic converter or other components.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.