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 deposits. 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.
1. Most Common Causes
- Clogged fuel injector due to debris or carbon buildup
- Faulty fuel injector (internal failure)
- Contaminated fuel (water, dirt, or poor quality)
- Fuel filter restriction causing low pressure
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine misfire or rough idle, especially on cylinder 5
- Reduced engine power and acceleration hesitation
- Poor fuel economy and increased emissions
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P02AC is present. Check freeze frame data for conditions.
Step 2: Perform a cylinder contribution test using a scan tool to confirm cylinder 5 is weak.
Step 3: Inspect fuel injector electrical connector and wiring for damage or corrosion.
Step 4: Use a noid light to test injector pulse; if no pulse, check ECM and wiring.
Step 5: Remove injector and perform flow bench test to confirm restriction; clean or replace as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances. A restricted injector can cause misfires, which may damage the catalytic converter and other engine components. Have it diagnosed and repaired promptly.
How much does it cost to fix?▼
Costs range from $150 to $400, depending on labor rates and whether the injector is cleaned or replaced. Replacement is more expensive but often necessary.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.