P16AF on 2018-2020 Chevrolet Traverse (L, LS, LT, RS, Premier, High Country) — Engine Controls Ignition Relay Feedback Circuit 2 Low Voltage
1 vehicles · 1 makes · $150-$900 repair
How to diagnose and fix P16AF: most-reported vehicles
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Chevrolet Traverse · 2018–2020
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)
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P16AF 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 P16AF mean?
P16AF stands for "Engine Controls Ignition Relay Feedback Circuit 2 Low Voltage." General Motors powertrain code. The Engine Control Module receives three ignition voltage feeds — two supplied through the engine controls ignition relay and one through the ignition main relay — and continuously compares them against each other. P16AF sets when the ECM measures less than about 5 volts on engine controls ignition relay feedback circuit 2 while that circuit should be energised. The module is reporting that one of its own power feeds has dropped out, which is why the fault presents as an electrical no-start or stall rather than as a sensor complaint. GM bulletins document the common root cause as low or no voltage at ECM connector X1, terminal 49 (circuit 5290), usually from poor terminal tension.
What are the most common causes of P16AF?
The most common causes of P16AF are: Poor terminal tension or a backed-out/spread terminal at ECM connector X1 pin 49 (circuit 5290) — the documented GM cause, Failed engine controls ignition relay or corroded relay socket in the underhood fuse block, Chafed, broken or corroded ignition feed wiring between the relay and the ECM, Loose or corroded fuse-block connections, or a fuse with poor contact, Weak battery or bad grounds causing voltage drop during cranking, Internal ECM fault. The specific cause varies by vehicle.
How much does it cost to fix P16AF?
Repair costs for P16AF range from $150 to $900, depending on the vehicle and root cause.
Which vehicles are affected by P16AF?
Au7o has documented P16AF across 1 vehicle models from 1 manufacturers: Chevrolet.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.