What it means
The control module detected a low electrical signal in the cylinder 10 injector B circuit. This indicates an electrical circuit condition; it does not by itself establish injector flow or cylinder fuel balance.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Cylinder 10 injector B is the injector identified for cylinder 10, and its driver circuit supplies the electrical command for injector operation. The control module monitors the response on this circuit and sets P21EE when the signal is lower than expected. The code indicates an electrical fault in the cylinder 10 injector B circuit and does not establish how much fuel the injector delivers.
Common causes
Most likely first.
- Short to ground in wiring
- Damaged or corroded connector
- Injector electrical fault
Symptoms
- Check-engine light on
- Rough running or misfire
- Reduced engine power
- Increased fuel consumption
How to diagnose it
- Save freeze-frame data and review live misfire counts and fuel trims to identify when the cylinder 10 injector B circuit fault occurs and whether cylinder 10 is misfiring.
- With the engine off, inspect the cylinder 10 injector B connector and harness for corrosion, loose terminals, chafing, or damaged insulation that could contact ground.
- Use the vehicle wiring diagram to check the cylinder 10 injector B circuit for a short to ground, an open, or a poor connection.
- With the circuit isolated according to the manufacturer's procedure, test the injector’s electrical condition and compare it with the manufacturer's specification.
- If the wiring and injector pass, test the cylinder 10 injector B driver circuit at the control module following the manufacturer's procedure.
Common fixes
- Clean and secure a corroded or loose cylinder 10 injector B connector.
- Repair a short to ground, open, or damaged wire in the cylinder 10 injector B circuit.
- Replace cylinder 10 injector B if its electrical test is outside the manufacturer's specification.
- Repair or replace the control module only if its cylinder 10 injector B driver fails the specified tests.
Can I keep driving?
If the engine runs smoothly and the warning light is steady, limit driving to necessary trips and avoid heavy acceleration. Stop if the light flashes, the engine misfires badly, or power drops sharply, because prolonged misfire can damage the catalytic converter.
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.