Cylinder 4 fuel injector leaking or delivering more fuel than commanded (worn or sticking); Carbon or deposit build-up on the injector tip altering spray and flow; Injector wiring, connector or terminal fault on cylinder 4 causing incorrect drive or resistance; Fuel pressure too high or fuel pressure regulation fault affecting delivery; Mechanical problem on cylinder 4 (low compression, air leak at the intake port) causing the control unit to over-correct; Outdated or faulty control unit calibration affecting the offset learning.

P02D2

Cylinder 4 Fuel Injector A Offset Learning At Min Limit.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
2: AreaFuel and air metering (injector circuit)
D2: FaultThe specific fault in that area

What it means

P02D2 means the engine control unit has learned an injector offset correction for the cylinder 4 fuel injector (circuit A) that has reached its minimum limit. The control unit trims each injector's delivery to match its measured behaviour, and for this injector the trim has run out of range in the reducing direction. This suggests that cylinder 4 is receiving more fuel than commanded, or that the injector is behaving out of tolerance. Exact learning method and limits vary by engine and manufacturer.

Symptoms

Engine warning light on
Rough idle or uneven running, possibly on cylinder 4
Slight misfire or hesitation under load
Increased fuel consumption
Black smoke or a rich exhaust smell
Hard starting or rough running after a cold start

Possible causes

Cylinder 4 fuel injector leaking or delivering more fuel than commanded (worn or sticking)likely
Carbon or deposit build-up on the injector tip altering spray and flowpossible
Injector wiring, connector or terminal fault on cylinder 4 causing incorrect drive or resistancepossible
Fuel pressure too high or fuel pressure regulation fault affecting deliverypossible
Mechanical problem on cylinder 4 (low compression, air leak at the intake port) causing the control unit to over-correctrare
Outdated or faulty control unit calibration affecting the offset learningrare

How to diagnose

Read all stored codes and freeze frame data, noting engine temperature, load and fuel trim values when the code set
Check for other injector, misfire or fuel trim codes that point to a wider fault
Inspect the cylinder 4 injector connector, terminals and wiring for damage, corrosion or looseness
Review live data for fuel trims and cylinder balance or misfire counters, comparing cylinder 4 with the others
Check fuel pressure against the manufacturer's specification at idle and under load
Measure the cylinder 4 injector's electrical resistance and check its drive signal against specification
Check for leaking or sticking injector using the manufacturer's recommended method, as procedure depends on engine type
Perform a compression test or check for intake leaks on cylinder 4 if the injector tests fine

How to fix

Replace the cylinder 4 injector if it is leaking, sticking or out of specification, and follow any manufacturer coding or learning procedure
Repair or replace damaged wiring, terminals or the connector for the injector
Correct fuel pressure faults by repairing the fault found in the fuel pressure control or supply
Repair the underlying mechanical or intake fault on cylinder 4
Clear the code and complete the relearn drive cycle to confirm the offset returns within range
Update the control unit calibration only where the manufacturer lists it as a known fix for this fault

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but book it in soon. A leaking or over-fuelling injector can wash oil from the bore, dilute the engine oil and damage the catalyst, so avoid long or hard driving if it runs roughly or smells of fuel.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.