What causes fault code P02A5?

• Most likely: Leaking or 'dripping' fuel injector on cylinder 2 • Likely: Faulty spark plug or ignition coil (incomplete combustion) • Possible: Wiring harness or connector issue to the injector (short to ground) • Rare: Internal engine mechanical fault, such as low compression or damaged valve in cylinder 2

How do you fix fault code P02A5?

STEP 1: Perform a visual inspection of the spark plug and ignition coil on cylinder 2. Look for carbon fouling indicating a rich condition. STEP 2: Test the fuel injector. Measure resistance (typically 12-16 Ohms for high-impedance or 2-5 Ohms for low-impedance). Use a stethoscope to verify the injector is 'clicking'. STEP 3: Monitor injector duty cycle using an oscilloscope or scan tool. A constantly open injector suggests a wiring short to ground or a faulty ECU driver. STEP 4: Swap the injector from cylinder 2 to cylinder 1. If the fault code follows to cylinder 1 (P02A1), the injector is defective and must be replaced.

Powertrain (Engine & Gearbox)Standard EOBD

P02A5 - Cylinder 2 – Fuel Trim at Max Limit (Rich Mixture)

Q: What are the symptoms of fault code P02A5?

• Check engine light (MIL) illuminated • Rough idling and engine vibrations • Increased fuel consumption • Smell of unburned fuel from the exhaust • Vehicle may enter 'Limp-home' mode

Last updated:1 February 2026

Related:Fuel Injector, Spark Plug, Ignition Coil, Engine Control Unit (ECU), Lambda-sensor / O2 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

The Engine Control Unit (ECU) monitors fuel trim for each individual cylinder using crankshaft speed fluctuations and oxygen sensor (Lambda) feedback. P02A5 is stored when the ECU has attempted to compensate for an excessively rich condition in cylinder 2 by reducing the fuel injector pulse width (negative fuel trim), but has reached its maximum adaptive limit. This suggests that cylinder 2 is receiving too much fuel or insufficient air compared to the other cylinders.

Possible Causes

Leaking or 'dripping' fuel injector on cylinder 2

Faulty spark plug or ignition coil (incomplete combustion)

Wiring harness or connector issue to the injector (short to ground)

Internal engine mechanical fault, such as low compression or damaged valve in cylinder 2

Symptoms

Check engine light (MIL) illuminated

Rough idling and engine vibrations

Increased fuel consumption

Smell of unburned fuel from the exhaust

Vehicle may enter 'Limp-home' mode

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P02A5 - Cylinder 2 – Fuel Trim at Max Limit (Rich Mixture)

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P02A5 - Cylinder 2 – Fuel Trim at Max Limit (Rich Mixture)

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