P0272

Cylinder 4 Contribution/Balance Fault

P0272 is a generic OBD-II powertrain diagnostic trouble code: Cylinder 4 Contribution/Balance Fault. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0272
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on, possible limp mode)
Need P0272 disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What P0272 means

P0272 — Cylinder 4 Contribution/Balance Fault — is set when the ECM detects that cylinder 4 is not contributing its expected share of torque to the crankshaft. The ECM evaluates this by monitoring crankshaft acceleration after each power stroke via the crankshaft position sensor: a healthy cylinder produces a distinct speed-up of the crank; a weak or dead cylinder produces little or no acceleration. When cylinder 4's contribution falls below a calibrated threshold, P0272 is logged.

Unlike the circuit-low/high codes (P0270/P0271), P0272 is a functional performance fault rather than a pure electrical one. It can result from electrical issues (injector circuit faults) but also from mechanical problems — low compression, a leaking head gasket, worn piston rings — or from ignition failure (bad spark plug or coil in petrol engines). On diesel engines, glow plug failure or a mechanically stuck injector can produce the same result.

Cylinder 4 exists in all four-or-more-cylinder engines. Because this code points to an underperforming cylinder rather than a specific component, a systematic diagnosis is required to distinguish between injector, ignition, and mechanical root causes before parts are replaced.

Common causes

Most-frequently reported root causes when P0272 is logged.

  • 1
    Clogged, stuck-closed, or electrically failed fuel injector on cylinder 4 delivering insufficient fuel.
  • 2
    Defective spark plug or ignition coil (petrol engines) causing intermittent or complete misfire on cylinder 4.
  • 3
    Low compression in cylinder 4 from worn piston rings, damaged valves, or a failing head gasket.
  • 4
    Failed or weak glow plug on cylinder 4 (diesel engines) reducing combustion efficiency especially when cold.
  • 5
    Fuel delivery problem — low fuel rail pressure or a clogged fuel filter reducing injector throughput.
  • 6
    Wiring or connector fault in the cylinder 4 injector circuit causing intermittent fuel delivery.
  • 7
    Air leak (vacuum leak or cracked intake manifold gasket) affecting only cylinder 4's air-fuel mixture.
  • 8
    ECM calibration or software fault causing incorrect fuel-delivery calculation for cylinder 4.

Symptoms drivers notice

Rough or uneven idle with a vibration that may ease slightly as engine speed rises.
Engine hesitation, jerking, or surging during acceleration under load.
Noticeable loss of power across the rpm range.
Poor fuel economy and potentially elevated exhaust smoke (black on petrol, white/grey on diesel).
MIL illuminated, often with a companion misfire code P0304.
Increased exhaust emissions at the tailpipe from incomplete combustion.

How to diagnose P0272

A typical diagnostic flow when this code is present.

  1. 1
    Scan for all codes and record live data including per-cylinder misfire counts and short/long-term fuel trims.
  2. 2
    Perform a cylinder contribution (cut-out) test using a scan tool: deactivate each injector in turn and monitor the rpm drop — a weak or no-drop response on cylinder 4 confirms the fault location.
  3. 3
    Inspect and test the cylinder 4 spark plug and ignition coil (petrol engines); swap with an adjacent cylinder to isolate the fault.
  4. 4
    Check fuel injector operation by swapping the cylinder 4 injector with an adjacent one and re-running the contribution test to see whether the fault moves.
  5. 5
    Perform a compression test and, if low, a leakdown test on cylinder 4 to rule out mechanical wear or a blown head gasket.
  6. 6
    Check fuel rail pressure at idle and under load against OEM specification; a low reading points to a pump or filter issue upstream.
  7. 7
    On diesel engines, test glow plug resistance and operation on cylinder 4 before condemning the injector.

Related powertrain codes

Frequently asked questions

What is the difference between P0272 and P0270/P0271 for cylinder 4?

P0270 and P0271 are electrical circuit faults — the ECM cannot command the injector because the control circuit voltage is out of range. P0272 is a functional performance fault — the ECM can send the signal but cylinder 4 is still not producing the expected power contribution. P0272 requires broader diagnosis including mechanical and ignition checks.

Can a bad spark plug cause P0272?

Yes, on petrol engines. A worn or fouled spark plug may fail to reliably ignite the mixture in cylinder 4, reducing its torque contribution below the ECM's threshold and triggering P0272 alongside a P0304 misfire code. Replacing spark plugs is a low-cost first step.

Is P0272 more serious on a diesel than a petrol engine?

Both are serious, but on diesel engines the code can indicate a mechanically stuck or leaking injector that is already causing internal engine damage (diluted oil, hydraulic lock risk). Diesel P0272 should be diagnosed without delay.

My scan tool shows P0272 and P0304 together — are they the same problem?

They are two views of the same event. P0304 is the misfire counter exceeding the threshold for cylinder 4; P0272 is the contribution/balance test failing for the same cylinder. Diagnosing the root cause of either code will resolve both.

Disabling P0272 in software

RaceTune can permanently disable P0272 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

Got P0272 in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file