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 certain 2019 3.6L LFY models built before February 22, 2019, flagged by ignition coil supply and ignition relay feedback codes and caused by loose terminal tension in the underhood fuse block. 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 (19-NA-119) addresses the no-crank codes by voltage-drop testing the underhood fuse block (X50A), repairing loose terminals, and replacing the fuse block if the drop exceeds specification. 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.
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Sources for this issue (2)
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.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.