Faulty or sticking cylinder 12 fuel injector, or one with a wear-related slow response; Wiring or connector fault in the cylinder 12 injector circuit (high resistance, corrosion, chafing); Low or unstable fuel rail pressure from a weak pump, blocked filter or pressure control fault; Crankshaft or camshaft position sensor signal fault or timing correlation error affecting injection timing; Mechanical timing fault such as a stretched chain or a jumped or incorrectly set drive; Engine control unit injector driver fault or outdated calibration.

P01E1

Cylinder 12 Injection Timing Performance - Over Retarded.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
E1: FaultThe specific fault in that area

What it means

P01E1 is a generic powertrain code meaning the actual injection timing for cylinder 12 is later than the commanded timing by more than the control unit allows. The engine control unit compares the commanded start of injection with the measured or estimated timing, and sets the code when the retard error persists. It applies to engines with at least twelve cylinders, so it is rare and the exact monitoring method depends on the engine.

Symptoms

Malfunction indicator lamp on
Rough running or misfire, mainly on one bank
Loss of power or poor throttle response
Hard starting or extended cranking
Increased exhaust smoke or fuel smell
Engine may enter limp mode

Possible causes

Faulty or sticking cylinder 12 fuel injector, or one with a wear-related slow responselikely
Wiring or connector fault in the cylinder 12 injector circuit (high resistance, corrosion, chafing)likely
Low or unstable fuel rail pressure from a weak pump, blocked filter or pressure control faultpossible
Crankshaft or camshaft position sensor signal fault or timing correlation error affecting injection timingpossible
Mechanical timing fault such as a stretched chain or a jumped or incorrectly set driverare
Engine control unit injector driver fault or outdated calibrationrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting load, speed, rail pressure and temperature when the code set
Check for related codes such as other cylinder injection timing, misfire, rail pressure or crank and cam correlation codes, and deal with those first
Inspect the cylinder 12 injector wiring and connector for damage, corrosion, moisture and poor pin tension
Check fuel quality, fuel filter condition and supply pressure against the manufacturer specification
Compare live data for rail pressure, injector correction values and misfire counters on cylinder 12 against other cylinders
Test the injector circuit resistance and driver signal with a suitable meter or scope, following the model-specific procedure
Check crankshaft and camshaft sensor signals and verify mechanical timing if correlation is in doubt
Check for a manufacturer software update relevant to this fault

How to fix

Repair or replace damaged wiring or connectors in the cylinder 12 injector circuit
Replace the cylinder 12 injector if testing shows it is faulty, and code or adapt it as the manufacturer requires
Replace a blocked fuel filter and repair any fuel supply or pressure control fault
Replace a faulty crankshaft or camshaft sensor, or correct the mechanical timing fault
Update the engine control unit calibration only if an outdated one is a documented cause for this engine

Can I keep driving?

Medium severity

Short, gentle journeys to a workshop are usually acceptable, but avoid heavy loads and high revs. If the engine runs roughly, misfires badly or goes into limp mode, stop driving and get it checked, as unburnt fuel can damage the catalytic converter and late injection can stress the engine.

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