Engine

P0272 — Cylinder 4 Contribution/Balance Fault

Severity: medium Drive with care, to a shop

What P0272 means

The engine control unit compares how much each cylinder contributes to crankshaft speed. P0272 is set when cylinder 4 falls noticeably behind the rest. The cause may be weak fuel delivery, poor spark or a mechanical problem inside that cylinder.

Symptoms

  • Check Engine light on
  • Rough or uneven idle
  • Reduced power and sluggish acceleration
  • Higher fuel consumption
  • Hesitation or stumbling under acceleration

Possible causes

  1. Faulty or clogged cylinder 4 fuel injector
  2. Damaged wiring or poor connection at the injector connector
  3. Low compression in cylinder 4 (rings, valves, head gasket)
  4. Worn spark plug or failing ignition coil on cylinder 4
  5. Vacuum leak near the cylinder 4 intake port
  6. ECM software fault or internal failure (rare)

How to diagnose

  1. Read all codes and freeze-frame data; look for related misfire codes such as P0304 or P0300.
  2. Inspect the injector and coil wiring and connectors at cylinder 4 for corrosion, breaks and chafing.
  3. Swap the cylinder 4 coil (and plug) with a neighbor and see whether the fault follows.
  4. Inspect the spark plug for wear, deposits, oil or fuel fouling.
  5. Test the injector: coil resistance, control pulse from the ECM, and operating click or noise.
  6. Check fuel pressure and look for vacuum leaks in the intake.
  7. Run a compression or leak-down test to rule out a mechanical fault.
  8. If everything checks out, look for an ECM software update.

Common fixes

  • Replace the spark plug or ignition coil on cylinder 4
  • Clean or replace the cylinder 4 fuel injector
  • Repair wiring or the connector and clean the contacts
  • Fix any intake vacuum leak
  • Repair the engine (valves, rings, head gasket) if compression is low
  • Reflash or replace the ECM as a last resort

Questions and answers

What does P0272 mean?

The ECM has found that cylinder 4 contributes less power than the other cylinders. The usual culprits are the injector, spark plug, coil or wiring, and less often low compression.

Can I drive with code P0272?

Only short distances with light loads. If the engine shakes badly or the check engine light flashes, stop driving, because misfires can damage the catalytic converter.

How can I quickly find the cause of P0272?

Swap ignition coils between cylinders and clear the code. If the fault moves to another cylinder, the coil is bad; if not, check the injector, wiring and compression.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.