P02A1

Code

Generic P — Powertrain

Cylinder 2 - Injector Leaking

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 34 RU: 24

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Page language: EN

Causes

Failed or stuck open fuel injector (internal leak)
Worn or damaged injector seals/O-rings allowing external leak into intake or crankcase
Leak in injector return/bleed line (diesel systems) or rail/drain passage
Low injector control resistance or short to battery causing partial opening
Faulty PCM or incorrect calibration (less common)
Fuel rail pressure regulator or check valve fault allowing backflow

Symptoms

Rough idle and/or misfire on cylinder 2
Poor fuel economy and increased emissions
Strong fuel smell or visible fuel leak near injector
Fuel dilution of engine oil (diesel especially)
Hard starting or extended cranking
Lower than normal fuel rail pressure or slow pressure recovery

What to check

Read freeze frame and stored data: fuel rail pressure, engine load, RPM, coolant temp when DTC set
Visual inspection for external fuel leaks at injector, rail, hoses and connectors
Inspect injector O-rings and seating for damage
Check injector harness and connector for corrosion, continuity, short to power or ground
Measure injector coil resistance and compare to spec
Perform cylinder contribution/balance or power balance test

Signal parameters

Injector coil resistance: typical solenoid 1–3 Ω (low-impedance) or 10–18 Ω (high-impedance) — check OEM spec
Injector activation pulse width: varies with load; steady battery-level supply when not driven
Fuel rail pressure: should remain within spec and not drop quickly when engine off or during cranking
Leakage threshold (diagnostic): any measurable leak when injector closed that allows fuel into cylinder or return path; manufacturer thresholds vary
Injector drive voltage: ~12 V supply, switched to ground by PCM; no constant supply when engine running except during commanded pulses

Diagnostic algorithm

Retrieve DTCs and freeze-frame data. Confirm P02A1 and note conditions when set.
Safety: relieve fuel system pressure and remove ignition sources before servicing injectors.
Visually inspect injector #2, O-rings, rail and nearby hoses for fuel. Repair visible external leaks.
With connector disconnected, check for fuel presence in the intake port (engine off, crank slowly). Excess fuel indicates leaking injector.
Measure injector coil resistance and compare to OEM spec. Abnormal values suggest internal failure.
Perform an injector on/off functional test (bidirectional scan tool) while monitoring fuel pressure; a leaking injector will cause persistent pressure drop or fuel flow during closed periods.
Perform a fuel rail pressure leak-down test: pressurize rail, isolate pump, monitor pressure. Rapid pressure loss indicates internal or external leak.
For diesel common-rail systems, perform return/bleed flow measurement on injector #2. Excess flow equals leaking injector.
Swap injector #2 with another cylinder (if identical) and re-run tests/clear codes to see if fault follows injector. Do not forget to mark and reinstall correctly.
If electrical anomaly suspected, check harness for short to power/ground and inspect PCM driver output. Repair wiring or replace PCM if proven faulty.
After repair or replacement, clear codes and road/test to confirm DTC does not return and symptoms are resolved.

Likely causes

Internal injector leakage (most common)
Damaged O-ring or sealing surface at injector
Clogged or damaged injector return/drain line (diesel)
Electrical fault causing continuous drive

Fault status

⚠️ Status

DTC P02A1 — Cylinder 2 injector leaking. PCM detected abnormal fuel flow or pressure behavior attributable to injector #2 allowing fuel when it should be closed.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours