Code
P02AC
Generic
P — Powertrain
Cylinder 5 - Injector Restricted
Views:
UK: 14
EN: 31
RU: 22
AI status
Completed
Completed
100%
Causes
- Clogged or partially blocked injector nozzle (carbon, varnish, debris)
- Contaminated or poor-quality fuel with particulates
- Collapsed or clogged injector inlet screen or fuel passage
- Stuck pintle or internal mechanical seizure in the injector
- Low fuel rail pressure or restricted fuel supply upstream (filter, feed line)
- Injector hydraulic damage (worn needle/seat) reducing flow
Symptoms
- Rough idle or vibration
- Cylinder-specific misfire (misfire detected on cylinder 5)
- Loss of power, hesitation or poor acceleration
- Increased fuel consumption or smoke (diesel) from exhaust
- Check Engine Light illuminated or stored DTC
- Poor cold start or uneven idle after warm-up
What to check
- Retrieve freeze-frame and live data with a scan tool; check for related codes (misfire, fuel pressure, rail sensor)
- Compare cylinder balance, injector pulse width and long/short term trims between cylinders
- Visual inspection of injector harness and connector for corrosion, damage or poor mating
- Inspect/replace fuel filter and check fuel supply lines for restriction
- Measure fuel rail/line pressure under idle and load conditions
- Measure injector coil resistance and compare to manufacturer spec
Signal parameters
- Injector pulse width and duty cycle (should vary with RPM/load and be comparable across cylinders)
- Injector coil resistance (ohms) and continuity vs. specification
- Injector current draw during activation (stable, no spikes/opens)
- Fuel rail pressure and its stability under load
- Cylinder contribution/trim values and misfire counters for cylinder 5
- Injector flow rate (ml/min) on a bench or flow tester compared to spec
Diagnostic algorithm
- Read and record DTCs, freeze frame data and live parameters. Note related codes (fuel pressure, misfire).
- Visually inspect injector connector, wiring harness and earthing points for damage or corrosion. Repair as needed.
- Check fuel supply: inspect/replace fuel filter, inspect fuel lines and fuel pump operation; verify correct rail pressure at idle and under load.
- Measure injector coil resistance and compare with specification. If out of range, suspect electrical or internal failure.
- Compare injector pulse widths and cylinder trims using a scan tool; if pulse width is normal but cylinder is lean, suspect flow restriction.
- If wiring and control appear normal, remove the injector and perform a bench flow/spray pattern test or send to professional cleaning/service. Inspect inlet screen/nozzle for debris and deposits.
- Swap the suspect injector with a known-good injector from another cylinder (if practical). If the problem moves with the injector, the injector is at fault.
- If bench testing indicates restricted flow and cleaning does not restore proper flow, replace the injector. Re-test operation and clear codes.
- After repair, verify fuel pressure, injector operation, cylinder contribution and that no related codes return.
Likely causes
- Injector nozzle clogged by deposits or debris
- Blocked fuel filter or blocked inlet screen to injector
- Injector internal mechanical failure (stuck pintle)
- Low rail pressure or intermittent fuel supply problem
- Contaminated tank fuel
Fault status
Status
Detected restricted fuel delivery at cylinder 5 injector. Possible reduced fuel flow or mechanical blockage causing cylinder-specific misfire/contribution imbalance.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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