What causes fault code P02F0?

• Most likely: Clogged or faulty fuel injector (Cylinder 4) • Likely: Incorrect IQA/IMA injector coding in the ECU • Possible: High resistance or corrosion in the wiring harness to injector 4 • Rare: Low engine compression in cylinder 4 due to mechanical wear or valve issues

Powertrain (Engine & Gearbox)Standard EOBD

P02F0 - Cylinder 4 Injector - Contribution/Balance Fault

Q: What are the symptoms of fault code P02F0?

• Check Engine Light (MIL) illuminated • Rough idling and engine vibrations • Reduced engine performance and poor acceleration • Increased fuel consumption • Engine knocking sounds under load

Q: How do you fix fault code P02F0?

STEP 1: Inspect the electrical connector for injector 4 for corrosion or loose pins. Clean as necessary. STEP 2: Test the injector circuit. Measure internal resistance (typically 0.2–0.5 Ohms for Piezo, 12–14 Ohms for Solenoid). Monitor the injection pulse with an oscilloscope. STEP 3: Verify that the correct IQA/IMA calibration code is programmed into the ECU for injector 4. Incorrect coding after replacement is a common cause. STEP 4: Perform a fuel return flow test (leak-back test) to compare cylinder 4 with the others. If injector 4 deviates significantly, replace it. STEP 5: If the issue persists, perform a mechanical compression test on cylinder 4.

Last updated:1 February 2026

Related:Injector, Engine Control Unit (ECU), CKP, Wiring, Fuel Pressure Sensor

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0200

Injector Circuit Malfunction

P0201

Cylinder 1 Injector Circuit Open

P0202

Injector Circuit - Cylinder 2 - Malfunction

P0203

Injector Circuit - Cylinder 3

Technical Description

P02F0 is stored when the Engine Control Unit (ECU) detects that cylinder number 4 is not contributing the expected amount of power or torque to the crankshaft. The ECU monitors crankshaft acceleration using the Crankshaft Position (CKP) sensor during each power stroke. If the acceleration increment for cylinder 4 is below a specific threshold compared to the other cylinders, a contribution/balance fault is triggered. This can be caused by electrical resistance issues in the injector, mechanical wear affecting the spray pattern, or fuel delivery deviations exceeding the fuel trim limits set by the IQA (Injector Quantity Adjustment) logic.

Possible Causes

Clogged or faulty fuel injector (Cylinder 4)

Incorrect IQA/IMA injector coding in the ECU

High resistance or corrosion in the wiring harness to injector 4

Low engine compression in cylinder 4 due to mechanical wear or valve issues

Symptoms

Check Engine Light (MIL) illuminated

Rough idling and engine vibrations

Reduced engine performance and poor acceleration

Increased fuel consumption

Engine knocking sounds under load

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P02F0 - Cylinder 4 Injector - Contribution/Balance Fault

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P02F0 - Cylinder 4 Injector - Contribution/Balance Fault

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