Cylinder 4 Injector Restricted
The P02A8 code indicates that the Engine Control Module (ECM) has detected a restriction in the fuel injector for cylinder 4. This means the injector is not delivering the correct amount of fuel, often due to clogging or internal damage. The ECM monitors fuel trim and injector flow rates; when cylinder 4 deviates significantly, it sets this code. A restricted injector can cause lean misfires, reduced power, and increased emissions.
1. Most Common Causes
- Clogged or dirty injector in cylinder 4 (carbon or varnish deposits)
- Blocked injector inlet screen (basket filter)
- Contaminated or low-quality fuel
- Wiring or connector issues on injector 4 (high resistance limiting opening current)
- Internal mechanical injector failure (stuck needle, broken spring)
- Faulty fuel pressure regulator (low overall pressure, though usually affects all cylinders)
- Defective PCM (damaged injector driver circuit - uncommon)
2. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Reduced fuel economy
- Hesitation or lack of power during acceleration
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Perform a fuel injector balance test using a scan tool to compare cylinder 4's contribution.
Step 3: Visually inspect the injector electrical connector and wiring for damage.
Step 4: Check fuel pressure and fuel filter condition.
Step 5: If injector is confirmed restricted, replace it and clear codes.
4. 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?▼
Replacing a single fuel injector typically costs $50-$150 for parts and labor, depending on vehicle make and model.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.