P02AC: Cylinder 5 - Injector Restricted

What it means

The control module detected restricted fuel flow through the cylinder 5 injector. The code identifies a flow restriction, but does not specify its cause.

At a glance

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

How it works

The engine computer monitors fuel delivery and combustion for cylinder 5. This code sets when it detects that cylinder 5's injector is delivering less fuel than expected, but it does not identify whether the restriction is in the nozzle, supply, or injector control.

Common causes

Most likely first.

1. Injector nozzle clogged or contaminated
2. Restricted fuel supply to injector
3. Injector electrical or control fault
4. Fuel contamination

Symptoms

• Check-engine light
• Rough idle or engine vibration
• Misfire or hesitation
• Reduced engine power

How to diagnose it

1. Check freeze-frame data and cylinder 5 misfire counts to see under what operating conditions the injector restriction is detected.
2. Inspect cylinder 5 injector connector and wiring for corrosion, damage, or a loose connection.
3. Compare cylinder 5's contribution and injector operation with other cylinders using a scan tool or suitable balance test.
4. Check for contamination and verify fuel supply to cylinder 5's injector using the applicable test procedure.
5. Test injector control and flow, and compare results with the manufacturer's specification before replacing parts.

Common fixes

• Repair a loose or damaged cylinder 5 injector connection.
• Clean a contaminated cylinder 5 injector if testing shows cleaning is appropriate.
• Replace a restricted cylinder 5 injector that fails a flow test.
• Correct contaminated fuel or restricted supply affecting the injector.

Can I keep driving?

If the engine runs smoothly, drive gently and have the cause checked soon; avoid heavy loads if it hesitates or misfires. Continued misfire can overheat and damage the catalytic converter.