P16A7 on Chevrolet: How to Diagnose & Fix
Engine Controls Ignition Relay Feedback Circuit 2
1 Chevrolet model · 1 documented issue · 1 critical · $150-$900 repair
P16A7 on Chevrolet by model: symptoms, diagnosis and fix
Many second-gen Traverse owners experience random no-crank / no-start events, sometimes after the engine shuts off while driving. GM service bulletins identify two patterns: bent or backed-out terminals at body connector X203 causing loss of communication on the HSLAN data bus with multiple stored DTCs, and a separate intermittent no-crank condition on 3.6L models flagged by crank/relay wake-up codes. The result is being stranded with a vehicle that will not respond to the start button.
Common Symptoms
- Intermittent no-crank when pressing start
- Engine shuts off while driving then won't restart
- Multiple unrelated warning lights / loss of communication
- Sometimes restarts after sitting
How to Fix
Have a technician scan for HSLAN/loss-of-communication DTCs and inspect/repair connector X203 for bent or damaged terminals per the GM bulletin; the second bulletin addresses the no-crank codes with module diagnosis and reprogramming. Owners should also rule out the simpler offenders first — loose/corroded battery terminals, a weak main battery, and a dead key-fob battery, all of which mimic the same symptom.
Sources for this issue (1)
P16A7 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P16A7 mean on a Chevrolet?
P16A7 stands for "Engine Controls Ignition Relay Feedback Circuit 2." A General Motors manufacturer-specific code (Chevrolet, GMC, Buick, Cadillac). The ECM receives three ignition-voltage feeds: two supplied by the engine controls ignition relay and one by the ignition main relay. It continuously compares the two monitored ignition-voltage circuits and sets P16A7 when the difference exceeds 3 volts for more than about 1 second. Because the ECM's own power supply is in question, symptoms range from a check engine light with no drivability complaint to hard starting, stalling, or a no-start. Note that P16A7 is manufacturer-specific — on non-GM vehicles the same code number carries a different definition, so confirm the make before diagnosing. On Chevrolet it is documented across 1 model: Traverse.
What are the most common causes of P16A7?
The most common causes of P16A7 are: Failed engine controls ignition relay, Open or shorted wiring in the ignition feed circuits to the ECM, Poor electrical connection — corroded, loose, or backed-out terminals in the underhood fuse/relay box, Blown fuse or poor ground in the ignition voltage supply, Water intrusion or corrosion in the fuse block, Failed ECM (rare — verify power and grounds first). The specific cause varies by vehicle.
How much does it cost to fix P16A7 on a Chevrolet?
Published repair estimates on Chevrolet range from $150 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P16A7 on a different make?
View P16A7 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.