P135A on 2018-2020 Chevrolet Traverse (L, LS, LT, RS, Premier, High Country) — Ignition Coil Supply Voltage Circuit Bank 1
1 vehicles · 1 makes · $150-$900 repair
Most Reported On
P135A is an OBD-II diagnostic trouble code meaning “Ignition Coil Supply Voltage Circuit Bank 1.” General Motors code (also used by Saab on GM-based engines), documented across Chevrolet, GMC, Buick, and Cadillac applications. The ignition system uses one coil per cylinder, and the engine control module monitors the power feed from the fuse to those coils. Per GM service information, the code sets when the ECM detects less than about 2.5 volts on the bank 1 ignition coil supply voltage circuit. Without proper coil supply voltage, spark on those cylinders is weak or absent, so the driver typically gets a check engine light, rough running, misfire, hard starting, or a no-start. It is usually a power-supply or wiring problem rather than a bad coil itself, so testing the feed before replacing parts saves money. 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
P135A 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 P135A mean?
P135A stands for "Ignition Coil Supply Voltage Circuit Bank 1." General Motors code (also used by Saab on GM-based engines), documented across Chevrolet, GMC, Buick, and Cadillac applications. The ignition system uses one coil per cylinder, and the engine control module monitors the power feed from the fuse to those coils. Per GM service information, the code sets when the ECM detects less than about 2.5 volts on the bank 1 ignition coil supply voltage circuit. Without proper coil supply voltage, spark on those cylinders is weak or absent, so the driver typically gets a check engine light, rough running, misfire, hard starting, or a no-start. It is usually a power-supply or wiring problem rather than a bad coil itself, so testing the feed before replacing parts saves money.
What are the most common causes of P135A?
The most common causes of P135A are: Blown ignition coil fuse or faulty relay feeding the coil supply circuit, Open, chafed, or corroded wiring in the coil supply harness, Corroded or backed-out connector at the ignition coil pack or harness junction, Poor engine or ECM ground causing voltage drop, Shorted ignition coil pulling down the shared supply circuit, Faulty engine control module driver or internal supply circuit (least common). The specific cause varies by vehicle.
How much does it cost to fix P135A?
Repair costs for P135A range from $150 to $900, depending on the vehicle and root cause.
Which vehicles are affected by P135A?
Au7o has documented P135A 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.