What it means
The control module detected a high electrical signal in the cylinder 5 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
Injector B is the second injector circuit identified for cylinder 5 by the control system; P21E5 points to an electrical signal issue, not confirmation of poor injector flow. The control module sets it when that circuit’s signal is higher than expected, which can result from a short to voltage, connector damage, or an injector electrical fault.
Common causes
Most likely first.
- Short to voltage 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
- Record freeze-frame data and check for cylinder 5 misfire or related injector codes to establish when the high signal occurs.
- Inspect the cylinder 5 injector B connector and harness for exposed conductors, loose pins, corrosion, or contact with another powered wire.
- Locate the circuit using the vehicle wiring information and check for a short to voltage with the circuit isolated as specified by the manufacturer.
- Check terminal fit and circuit continuity with injector B disconnected according to the manufacturer’s procedure.
- Test the electrical condition of injector B for cylinder 5 against the manufacturer’s specification.
Common fixes
- Secure the cylinder 5 injector B connector and clean or replace corroded terminals.
- Repair insulation damage or a short to voltage in the cylinder 5 injector B wiring.
- Replace a damaged connector or terminal that cannot maintain proper contact.
- Replace injector B for cylinder 5 if it fails the manufacturer’s electrical test.
Can I keep driving?
Reduce engine load if it misfires or loses power; continued misfiring can increase emissions and overheat the catalytic converter. Stop driving if it runs severely unevenly 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.