P21E7: Cylinder 6 Injector B Circuit High

What it means

The control module detected a high 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

Cylinder 6 injector B is one of the fuel injectors serving cylinder 6, and its driver circuit carries the command that controls injector operation. The control module monitors the electrical response on this specific circuit; P21E7 sets when that response is higher than expected. A high circuit reading points to an electrical fault and does not confirm whether the injector is delivering the right amount of fuel.

Common causes

Most likely first.

1. Short to voltage in wiring
2. Damaged or corroded connector
3. Injector electrical fault

Symptoms

• Check-engine light on
• Rough running or misfire
• Reduced engine power
• Increased fuel consumption

How to diagnose it

1. Save freeze-frame data and check live misfire and fuel-trim information to see when the cylinder 6 injector B fault occurs and whether cylinder 6 is also misfiring.
2. With the engine off, inspect the cylinder 6 injector B connector and nearby harness for corrosion, loose pins, chafing, heat damage, or contact with a power source.
3. Check the wiring between injector B for cylinder 6 and its control-module connection for a short to voltage or an open, following the vehicle wiring diagram.
4. With the circuit safely isolated as specified by the manufacturer, compare the injector’s electrical condition with the manufacturer's specification and check whether the high reading remains with the injector disconnected.
5. If the wiring and injector pass, test the injector driver circuit at the control module using the manufacturer's procedure before considering a module fault.

Common fixes

• Clean and secure a corroded or loose cylinder 6 injector B connector.
• Repair wiring shorted to voltage or damaged near the cylinder 6 injector B harness.
• Replace cylinder 6 injector B if its electrical test is outside the manufacturer's specification.
• Repair or replace the control module only if its injector B driver for cylinder 6 fails the specified tests.

Can I keep driving?

If the engine runs smoothly and the warning light is steady, limit driving and avoid heavy acceleration until the circuit is repaired. Stop driving if the light flashes, the engine misfires badly, or power drops sharply, since an active misfire can damage the catalytic converter.