What it means
The control module detected a low electrical signal in the cylinder 6 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 6 by the control system; this code reports an electrical signal problem and does not alone show whether fuel delivery is correct. The control module sets P21E6 when the cylinder 6 injector B signal is below its expected level, commonly because of a short to ground, a poor connection, or an injector electrical fault.
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
- Check freeze-frame data and scan for cylinder 6 misfire or related injector codes to see when the low signal was detected.
- Inspect the cylinder 6 injector B connector and harness for corrosion, loose pins, chafing, broken insulation, or pinched wiring.
- Use the vehicle wiring information to identify the circuit and check for a short to ground.
- Isolate the circuit as directed by the manufacturer, then check wiring continuity and connector terminal condition.
- Measure injector B’s electrical condition for cylinder 6 and compare it with the manufacturer’s specification.
Common fixes
- Reconnect and secure the cylinder 6 injector B connector; clean corrosion if present.
- Repair damaged wiring or a short to ground in the cylinder 6 injector B circuit.
- Replace a damaged connector terminal that cannot maintain a sound connection.
- Replace injector B for cylinder 6 if it fails the manufacturer’s electrical test.
Can I keep driving?
Avoid hard acceleration if the engine runs rough or has reduced power, since continued misfiring can increase emissions and damage 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.