Cylinder 5 Injector Restricted
The P02AC code indicates that the Engine Control Module (ECM) has detected a restriction in the fuel injector for cylinder 5. This means the injector is not delivering the proper amount of fuel, often due to clogging from debris, varnish, or carbon buildup. The ECM monitors fuel trim and injector flow rates; when cylinder 5's contribution is significantly lower than expected, this code is set. A restricted injector can cause lean misfires, reduced power, and increased emissions.
01. Most Common Causes
- Clogged fuel injector due to debris or varnish
- Carbon buildup on injector tip
- Contaminated fuel (water, dirt)
- Faulty fuel injector (internal failure)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Reduced power and acceleration
- Poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Perform a cylinder contribution test to confirm cylinder 5 is weak.
Step 3: Inspect fuel injector electrical connector and wiring for damage.
Step 4: Use a noid light to verify injector pulse from ECM.
Step 5: Remove injector and test flow and spray pattern on a bench.
Step 6: If restricted, clean or replace injector; also check fuel pressure and quality.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as a restricted injector can cause misfires, catalytic converter damage, and poor performance. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including diagnostic time and replacement of the injector. Cleaning may be cheaper but is less reliable.