P021D: Cylinder 10 Injection Timing

What it means

The PCM detected a problem with injection timing for cylinder 10. The precise monitoring method and cause depend on the engine and injection system.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

The injection system controls when fuel reaches cylinder 10, though the timing method varies among engines. The PCM monitors cylinder 10's injection timing or injector response and sets P021D when the timing behavior for that cylinder does not meet the expected range.

Common causes

Most likely first.

1. Injector timing or response fault
2. Injector wiring or connector fault
3. Fuel injector fault

Symptoms

• Check-engine light on
• Rough running or misfire
• Reduced engine power
• Hard starting

How to diagnose it

1. Record freeze-frame data and related codes, noting when cylinder 10's rough running or hard starting occurs.
2. Use vehicle service information to locate cylinder 10, then inspect its injector connector and wiring for chafing, corrosion, or looseness.
3. Check cylinder 10's injector control circuit for opens, shorts, and poor connections using the manufacturer's procedure.
4. Compare cylinder 10's injector timing or response data with the other cylinders using a compatible scan tool.
5. If wiring checks pass, verify fuel pressure and test cylinder 10's injector response against the manufacturer's specification.

Common fixes

• Repair damaged wiring or a loose connection at the cylinder 10 injector.
• Clean or repair corroded cylinder 10 connector terminals.
• Replace a cylinder 10 injector that fails testing.
• Correct a confirmed fuel-pressure or delivery fault.
• Repair a verified timing-control or mechanical fault affecting cylinder 10.

Can I keep driving?

Avoid towing or hard acceleration if the engine misfires or has reduced power, because continued misfiring can damage the catalytic converter. Stop if the warning flashes or the engine runs severely rough.