What does code P0354 mean on a Hummer and is it safe to drive?
P0354: Ignition Coil D Primary/Secondary Circuit Malfunction. Here's what it means on your Hummer, what usually causes it, what repairs typically cost, and how safe it is to keep driving.
PowertrainHigh urgency
What this code means
Fault in ignition coil D circuit (cylinder 4). This is the fourth coil in a coil-on-plug system. Diagnosis mirrors P0351–P0353 but targets cylinder 4.
Common causes for your Hummer
- Failed ignition coil on cylinder 4
- Worn or fouled spark plug on cylinder 4
- Damaged coil wiring or connector
Symptoms
- Check Engine Light on or flashing
- Rough idle or misfire on cylinder 4
- Reduced performance
Typical fixes
- Replace ignition coil for cylinder 4
- Replace spark plug on cylinder 4
- Inspect coil connector and wiring
Repair cost range
For a Hummer, repairs for P0354 often fall between $80 and $300, depending on the cause and whether you use OEM or aftermarket parts. Labor rates vary by location.