P0272
Cylinder 4 Contribution/Balance
When a vehicle powertrain module registers the fault code P0272, it points directly to an internal system malfunction identified as "Cylinder 4 Contribution/Balance". Operating your engine under this condition may degrade long-term fuel maps.
Driver's Summary
Code P0272 means your vehicle detected a problem with the cylinder 4 contribution/balance system. The most common signs are misfire, rich or lean exhaust smell, loss of power. Stop driving as soon as it is safe to do so. This fault can lead to expensive secondary damage if left unaddressed.
Symptoms
Misfire, rich or lean exhaust smell, loss of power
Common Causes
- Clogged Cyl 4 injector
- Failed spark plug
- Broken piston ring
- Bad PCM injector driver
How to Fix
- 1 Clean or replace injector
- 2 Replace spark plug
- 3 Rebuild engine block
- 4 Replace PCM
Technical Explanation
P0272 is stored after the control module confirms the fault over multiple ignition cycles, ruling out transient electrical noise as the cause. For injector-specific codes, the ECM monitors the injector control circuit voltage drop during each pulse; a shorted or open injector presents a characteristic resistance signature that differs measurably from a healthy unit. Once confirmed, the code is stored as a permanent DTC and the MIL is activated. The freeze frame snapshot — recording RPM, load, coolant temperature, and fuel trim at fault detection — is also saved and is critical for accurate diagnosis.
Is It Safe to Drive?
With P0272 active, your engine or transmission is not operating within design parameters. Short-term driving may seem fine, but internal damage is accumulating — particularly to clogged cyl 4 injector.
Mechanic's Pro Tip
Module replacement should always be the last resort for P0272 after exhaustively verifying all power supply circuits, ground connections, and communication bus wiring. Use a wiring diagram to locate all fuses, relays, and ground points for the affected module, and measure voltage drop on each ground with the circuit loaded. A module "failure" is frequently a corroded ground eyelet or a weak battery causing brownout conditions — fix these first and you'll save hundreds of dollars on an unnecessary module replacement.
Injector: 150 - 400; Engine rebuild: 2,500+