What it means
The ECM cannot read a valid ion current signal from cylinder 1. Ion current sensing relies on the spark plug acting as an electrode after combustion.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The ECM monitors an ion-current signal associated with cylinder 1 to assess what happens in the combustion chamber after the spark. This code sets when the ECM cannot obtain a valid cylinder 1 signal, so it may not be able to assess that cylinder's combustion reliably.
Common causes
Most likely first.
- Ion sense module failed
- Wiring or connector fault
Symptoms
- Check-engine light on
- Rough idle or engine misfire
- Reduced engine performance
How to diagnose it
- Record freeze-frame data and check live misfire counts for cylinder 1, along with any ignition or fuel-system codes that could point to a combustion problem.
- Inspect cylinder 1's ignition and ion-sense connectors and visible wiring for loose pins, corrosion, damage, or poor routing near the ignition coil.
- Inspect the cylinder 1 spark plug for fouling or damage and verify that the installed plug is correct for the vehicle.
- Using the manufacturer's wiring diagram, check continuity and shorts in the cylinder 1 ion-current sensing path and its connectors.
- If wiring and the plug check out, follow the manufacturer's procedure to test the ion-sense module and its inputs before replacing parts.
Common fixes
- Reconnect or repair a loose or damaged cylinder 1 ion-sense connector.
- Repair damaged wiring in the cylinder 1 sensing path.
- Replace a fouled or damaged cylinder 1 spark plug with the specified type.
- Replace the ion-sense module if testing confirms it has failed.
Can I keep driving?
If the engine runs smoothly, limit driving and have the fault checked soon because a misfire can raise emissions and damage the catalytic converter. Stop driving if the engine misfires severely, loses power, or the warning light flashes.
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.