What it means
Ignition C control signal stuck high — short to B+. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The PCM sends Ignition C control signals to the ignition hardware and monitors the circuit's electrical state. This code sets when the Ignition C control line is held high, commonly because it is shorted to battery voltage, so the associated ignition channel may not switch correctly.
Common causes
Most likely first.
- Short to B+
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Rough running or misfire
- Hard starting or no start
- Reduced engine power
How to diagnose it
- Record freeze-frame data and review live misfire or ignition data to establish whether the high signal coincides with rough running or starting trouble.
- Inspect the Ignition C control wire and connector for insulation damage, corrosion, moisture, pushed-back pins, or contact with a power wire.
- Using the vehicle wiring information, check whether the Ignition C signal is shorted to battery voltage and identify where the unwanted connection begins.
- Wiggle the Ignition C harness while monitoring the signal to find an intermittent contact with a B+ source.
- If the harness and terminals are sound, test the Ignition C ignition component and PCM driver using the manufacturer's procedure.
Common fixes
- Repair the Ignition C wire where it has contacted a battery supply.
- Clean or replace corroded or loose Ignition C connector terminals.
- Reroute and secure wiring that is pinched against a power source.
- Replace a confirmed faulty ignition component or PCM driver.
Can I keep driving?
With rough running or misfiring, avoid hard acceleration and long trips because the ignition fault can worsen engine operation and emissions. If the engine stalls or will not start reliably, do not drive it until diagnosed.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.