Cylinder 4 - Injector Restricted
What it means
P02A8 means cylinder 4's fuel injector is flowing less fuel than commanded — it's partially clogged or restricted. The ECM detects that cylinder 4 needs more fuel than it can deliver, so that cylinder runs lean and may misfire, especially under load.
Can I keep driving? Driveable, but a restricted cylinder 4 injector leans out and misfires that cylinder; fix it before long trips.
Real-world scan data
Appears alongside · share of P02A8 scans
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Rough idle or misfire on cylinder 4
- Hesitation and reduced power under load
- Possible hard starting
Common causes
Most likely first
- Clogged or restricted cylinder 4 injector (deposits)Likely
- Poor-quality or contaminated fuelCommon
- Low fuel pressure or a restricted fuel filterCommon
- Wiring or connector fault on the injector (less likely)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame and confirm which cylinder is affected.
- Check fuel pressure and filter condition.
- Run an injector-balance or flow test on cylinder 4.
- Try a quality injector cleaner; if flow is still low, clean or replace the cylinder 4 injector.
- Clear the code and re-test under load.
FAQ
Quick answers
Is it safe to drive with P02A8?+
Can I just clear P02A8?+
Related codes
Read & clear P02A8 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.