Cylinder 3 fuel injector worn, sticking, clogged or leaking so its delivery is outside the learnable range; Wiring or connector fault on the cylinder 3 injector circuit, such as high resistance, corrosion or a poor pin fit; Fuel pressure problem (pump, regulator or pressure sensor) affecting delivery; Mechanical issue on cylinder 3 such as low compression or an air leak at that inlet port, causing the ECU to over-correct; Injector driver fault or a fault inside the ECU; Newly fitted injector not coded or adapted to the ECU where the system requires it.

P02D1

Cylinder 3 Fuel Injector A Offset Learning At Max 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)
D1: FaultThe specific fault in that area

What it means

P02D1 means the engine control unit has learned an injector offset correction for cylinder 3 and that correction has reached its maximum permitted limit. The ECU trims the injector's delivery or timing to match the real flow of that injector, and here it can no longer compensate. The fault points to the cylinder 3 injector or something affecting its delivery, and the exact learning method varies by engine and fuel system.

Symptoms

Rough idle or uneven running, mainly on cylinder 3
Misfire or hesitation under load
Engine management light on
Poor fuel economy or reduced power
Hard starting or extended cranking
Increased exhaust smoke or fuel smell

Possible causes

Cylinder 3 fuel injector worn, sticking, clogged or leaking so its delivery is outside the learnable rangelikely
Wiring or connector fault on the cylinder 3 injector circuit, such as high resistance, corrosion or a poor pin fitpossible
Fuel pressure problem (pump, regulator or pressure sensor) affecting deliverypossible
Mechanical issue on cylinder 3 such as low compression or an air leak at that inlet port, causing the ECU to over-correctpossible
Injector driver fault or a fault inside the ECUrare
Newly fitted injector not coded or adapted to the ECU where the system requires itrare

How to diagnose

Read all stored and pending codes plus freeze frame data, and note any other injector, misfire or fuel trim codes
Check live data for cylinder 3 misfire counts, injector correction values and fuel trims compared with the other cylinders
Inspect the cylinder 3 injector connector and wiring for damage, corrosion, chafing and bent or loose pins
Check fuel pressure against specification at idle and under load, following the procedure for that engine
Measure the cylinder 3 injector circuit resistance and check its signal and operation against the other cylinders
Check for inlet air leaks, vacuum leaks and fuel leaks around cylinder 3
Carry out a compression or leak-down test on cylinder 3 if the injector and fuel supply check out
Where the engine design allows, swap the cylinder 3 injector with another cylinder to see whether the fault follows it

How to fix

Replace the faulty cylinder 3 injector and carry out any injector coding or adaptation the manufacturer requires
Repair or replace damaged wiring, terminals or connectors on the injector circuit
Repair the fuel supply fault found, such as a failing pump, regulator or pressure sensor
Fix any inlet air or fuel leak at cylinder 3
Repair the mechanical fault in cylinder 3 if compression is low
Clear the code and run the relearn or adaptation routine, then road test to confirm it does not return

Can I keep driving?

Medium severity

The car can usually be driven carefully for a short time, but book it in soon because a poorly delivering injector can cause misfires, higher emissions and possible catalytic converter or engine damage. Avoid heavy loads and stop driving if it misfires badly or the warning light flashes.

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