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
Most Reported On
P16AF is an OBD-II diagnostic trouble code meaning “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. This code is most commonly reported on 2018-2020 Chevrolet Traverse (L, LS, LT, RS, Premier, High Country), with repair costs ranging from $150 to $900.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
P16AF does not use the standard P/B/C/U prefix. It may be a manufacturer-specific code, so verify that a scanner supports your exact year, model and module before buying.
FAQ
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.