Faulty ignition coil or spark plug on cylinder 4; Faulty, blocked or leaking fuel injector on cylinder 4, or a fault in its wiring; Damaged wiring or poor connector contact to the cylinder 4 injector or coil; Vacuum or intake leak affecting cylinder 4, such as a leaking manifold gasket or intake seal; Low compression on cylinder 4 from a burnt valve, worn rings or head gasket leak; Valve train problem on cylinder 4, such as a worn cam lobe, collapsed lifter or valve timing fault (depends on engine); Fault in the ECU driver circuit for cylinder 4.

P0272

Cylinder 4 Contribution/Balance.

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)
72: FaultThe specific fault in that area

What it means

P0272 means the engine control unit has detected that cylinder 4 is not contributing as much as the other cylinders during the cylinder balance or contribution test. It usually sets when the ECU sees a speed or torque change from cylinder 4 that is outside the expected range. The generic definition does not say whether the cause is fuel, ignition, air or mechanical, so diagnosis has to establish which.

Symptoms

Rough idle or a noticeable engine shake
Misfire or hesitation under load, mainly on cylinder 4
Loss of power and sluggish acceleration
Engine management light on, possibly flashing during a heavy misfire
Increased fuel consumption
Fuel smell or raised exhaust emissions

Possible causes

Faulty ignition coil or spark plug on cylinder 4likely
Faulty, blocked or leaking fuel injector on cylinder 4, or a fault in its wiringlikely
Damaged wiring or poor connector contact to the cylinder 4 injector or coilpossible
Vacuum or intake leak affecting cylinder 4, such as a leaking manifold gasket or intake sealpossible
Low compression on cylinder 4 from a burnt valve, worn rings or head gasket leakpossible
Valve train problem on cylinder 4, such as a worn cam lobe, collapsed lifter or valve timing fault (depends on engine)rare
Fault in the ECU driver circuit for cylinder 4rare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting load, speed and temperature when the fault set, and check for related misfire codes such as P0304
Inspect the cylinder 4 coil, injector connectors and wiring for damage, corrosion, heat damage or loose pins
Remove and inspect the cylinder 4 spark plug for wear, fouling, wet fuel or oil, and compare with the other plugs
Swap the cylinder 4 coil with another cylinder, clear the codes and see whether the fault moves; repeat with the spark plug if needed
Check live misfire counters and fuel trim data, and look for intake leaks around cylinder 4 with a smoke test
Test the injector for correct resistance and operating signal, and check for a proper injector pulse from the ECU
Carry out a compression or cylinder leakage test on cylinder 4 if ignition and fuel checks are clear
Check valve timing and valve train condition where the engine design or test results point that way

How to fix

Replace the faulty ignition coil and/or spark plugs, using the correct specification for the engine
Clean or replace the cylinder 4 injector if it is faulty or blocked
Repair or replace damaged wiring or connectors in the affected circuit
Replace leaking intake gaskets or seals and repair any vacuum leaks
Repair the mechanical fault found, such as valve, piston ring or head gasket work, following the manufacturer's procedure
Where the ECU driver is confirmed faulty, repair or replace the control unit as the manufacturer directs

Can I keep driving?

Medium severity

Short, gentle driving is usually possible, but get it checked soon because a continued misfire can overheat and damage the catalytic converter. If the engine light flashes or the engine runs very roughly, stop driving and have it recovered.

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