P02D5

Code

Generic P — Powertrain

Cylinder 5 Fuel Injector A Offset Learning At Max Limit

Brand: Generic

Type: P — Powertrain

Views: UK: 28 EN: 47 RU: 29

AI status

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Page language: EN

Causes

Worn, clogged, leaking, or electrically faulty fuel injector on cylinder 5
Poor electrical connection or damaged wiring in injector control circuit (open, short to ground/voltage)
Low or unstable fuel rail pressure or failed fuel pressure regulator
Cylinder mechanical problems (low compression, valve issues)
Intake vacuum leak or faulty MAF/MAP causing incorrect fueling
PCM software bug or lost adaptation data

Symptoms

Check Engine Light (malfunction indicator lamp)
Rough idle or vibration, especially at idle or light load
Reduced engine performance and acceleration
Increased fuel consumption and emissions
Intermittent or persistent misfire on cylinder 5

What to check

Read freeze frame and live data (fuel trims, injector pulse width, misfire counters, fuel rail pressure, battery voltage)
Check stored and pending codes; see if code returns after clear
Verify fuel rail pressure and regulator operation under load
Measure injector electrical resistance and compare to spec
Scope or monitor injector waveform/pulse on cylinder 5
Inspect connector and wiring for corrosion, breaks, loose pins, or damaged insulation

Signal parameters

Injector pulse width (ms)
Injector duty cycle (%)
Learned injector offset/correction value (µs or %)
Short-term and long-term fuel trims (STFT/LTFT)
Cylinder-specific misfire counters
Fuel rail pressure (kPa/psi/bar)

Diagnostic algorithm

Retrieve all codes and freeze frame; record current learned offset, STFT/LTFT, injector pulse width and misfire data for cylinder 5.
Clear codes and perform a controlled road test or run at conditions that reproduce the fault while monitoring live data to confirm repeatability.
Verify fuel system: check fuel pressure static and under load, inspect fuel filter and pump operation.
Test injector electrical circuit: measure resistance at the injector, check for proper supply and driver signals, backprobe and scope injector waveform. Repair wiring/connector issues.
Swap injector 5 with another cylinder and re-run the test. If the code/symptoms move with the injector, replace or professionally service the injector.
If injector swap does not move the fault, perform compression and/or leak-down test on cylinder 5 to identify mechanical problems.
Inspect intake system and sensors (MAF, MAP, vacuum lines) that could cause incorrect fueling and large trims.
If hardware checks OK, check for PCM software updates or reset adaptation and relearn per manufacturer procedure; verify if code returns.
After repairs, clear codes and perform a final verification drive to ensure learned offset returns within normal range and fault does not reappear.

Likely causes

Injector on cylinder 5 is weak, partially clogged, stuck, or leaking
Connector corrosion or broken wire at injector 5
Fuel pressure low due to pump, filter, or regulator
Cylinder 5 has low compression or a mechanical fault
PCM reached correction limit after long-term fuel trim attempts

Fault status

⚠️ Status

PCM reports that the learned correction for Cylinder 5 Fuel Injector A has reached its maximum limit and cannot fully correct the imbalance.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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