What it means
The primary control voltage at ignition coil C exceeds the upper limit, suggesting a short to battery or an open primary winding.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Ignition coil C uses its primary circuit to build the charge that produces spark at its assigned plug. The engine control module monitors coil C's primary control signal and sets this code when the signal is higher than expected, often because the control circuit is open or shorted to battery voltage.
Common causes
Most likely first.
- Primary shorted to battery
- Open primary winding
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light on, possibly flashing
- Engine misfire or rough idle
- Hesitation under acceleration
- Reduced power
How to diagnose it
- Save freeze-frame data and review live misfire counts to see when the cylinder served by coil C is affected.
- Inspect coil C's connector and primary wire for a disconnected plug, broken conductor, corrosion, or damage that could leave the circuit open.
- Check for loose or corroded terminals and make sure coil C's connector is fully seated.
- Using the wiring diagram, test coil C's primary control wire for an open or a short to battery voltage, then test the winding to the manufacturer's specification.
- If the coil and wiring pass, check the ECU driver circuit using the manufacturer's diagnostic procedure.
Common fixes
- Reconnect coil C's loose connector or clean and secure its terminals.
- Repair an open primary wire or a short to battery voltage.
- Replace coil C if its primary winding is open.
- Repair the ECU driver circuit if testing confirms it is faulty.
Can I keep driving?
If the check-engine light flashes or the engine misfires heavily, stop driving when safe because continued misfiring can damage the catalytic converter. With a steady light and smooth running, keep any necessary trip short and avoid hard acceleration.
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.