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Severity: Moderate Code type: Generic (all makes)

P0272 Code: Cylinder 4 Contribution/Balance

The ECU can't balance cylinder 4 against the rest anymore; its fuel correction is outside the limit.

Safety first · Consult a professional

  • Fuel vapor is flammable. No smoking or open flames; work outdoors and fix fuel leaks before driving.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Cylinder 4 Contribution/Balance
System
Fuel & Air Metering · Powertrain
Safe to drive?
With caution
Typical repair cost
$250–$4,200
DIY difficulty
Hard

P0272 means the engine computer's per-cylinder fuel correction for cylinder 4 has reached its limit, either adding fuel to a weak cylinder or pulling it from one that over-delivers. In the US you'll meet it most often on Volkswagen and Audi TDI cars: the Jetta, Golf, Beetle, Passat and A3 diesels. On those transverse engines cylinder 4 is at the transmission end, the driver's side of the engine bay. The older pump-injector TDI engines add a failure the common-rail ones don't have: each injector is driven by its own lobe on the camshaft, and if that lobe or its roller rocker wears, injector 4 simply delivers less fuel no matter what the computer asks. Common-rail TDIs are more often down to a worn injector or a leaking injector seal. On a V8 diesel, cylinder 4 is the second on the driver side of the Power Stroke 6.0 and 6.4, the rearmost on the passenger side of the 6.7, and the second on the passenger side of a Duramax.

Can I keep driving? Drivable, but don't put it off: a worn cam lobe gets worse quickly and throws metal into the oil, and a leaking injector can dilute the oil. Stick to normal driving until the measuring block values have been checked.

How to read P0272

How to read P0272P10223724
  1. P Powertrain
  2. 0 Generic (SAE)
  3. 2 Fuel & air (injector circuit)
  4. 72 Specific fault

Symptoms

  • Rough, shaking idle, often worse when cold
  • Slight stumble at light throttle
  • Fuel economy dropping below what the car usually gets
  • Tapping from the valve cover area on pump-injector engines
  • Black smoke or soot on acceleration

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Injector 4 worn or leaking internally 32%
  2. Pump-injector engines: worn camshaft lobe or roller rocker for injector 4 16%
  3. Low compression in cylinder 4 13%
  4. Injector 4 sealing washer leaking, with carbon around the injector 12%
  5. Uneven intake carbon from the EGR system restricting cylinder 4 10%
  6. Injector 4 wiring or the harness under the valve cover (pump-injector engines) 10%
  7. Replacement injector without its correction value coded 7%

Diagnosis step by step

Diagnostic flow: P02721Read the per-cylinder values2Find cylinder 43Leak-off test on common-rail engines4Inspect the cam on pump-injectorengines5Check compression6Code and verify

  1. Read the per-cylinder values

    With a VW-capable scan tool, read the injection quantity deviation for all four cylinders at warm idle. On pump-injector TDIs, measuring block 013 is commonly held within about ±2.8 mg per stroke; common-rail TDIs show similar correction values in their own blocks.

    Tools: OBD-II scanner

  2. Find cylinder 4

    On transverse TDI engines, cylinder 1 is at the timing belt end on the passenger side, so cylinder 4 sits at the transmission end on the driver side. The injector and its connector are under the engine cover and, on pump-injector engines, under the valve cover.

    Tools: Flashlight

  3. Leak-off test on common-rail engines

    Disconnect the return lines, attach clear tubes or measuring vials to each injector and run the engine for a few minutes. An injector returning much more than the others, often double, is leaking internally.

    Tools: Towels & shallow pan, Gloves

  4. Inspect the cam on pump-injector engines

    Remove the valve cover and inspect the injector cam lobe and roller rocker for cylinder 4. Pitting, a flat spot or a scored roller confirms wear; replacing the injector alone won't fix it.

    Tools: Flashlight, Torque wrench

  5. Check compression

    Use a diesel adapter in the glow plug bore. TDI engines are typically around 360-450 psi when healthy, with a wear limit near 275 psi and no more than roughly 70 psi between cylinders.

    Tools: Compression tester

  6. Code and verify

    After any injector replacement, enter the new injector's correction value if the engine uses one, then recheck the deviation values warm. They should sit close to the other cylinders.

    Tools: OBD-II scanner

Where the parts are

Air intake and fuel metering – P027212345678
Air intake and fuel metering
  1. 1MAF sensor
  2. 2Turbocharger
  3. 3Throttle body
  4. 4Intake manifold
  5. 5Fuel injector
  6. 6EGR valve
  7. 7Fuel pump
  8. 8Thermostat

Repair options & costs

RepairDIY?Estimated cost
Replace injector 4 seal and hold-down bolt No $250–$550
Replace injector 4 (with coding) No $600–$1,200
Replace camshaft and rockers (pump-injector) No $1,500–$3,000
Clean intake manifold and ports No $400–$1,000
Replace all four injectors No $2,200–$4,200

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Volkswagen

Pump-injector TDI engines in the Jetta, Golf and Beetle are known for camshaft lobe and rocker wear, especially when oil that doesn't meet VW's diesel specification is used. A single cylinder with falling injection quantity is often the first sign.

Emissions / smog test impact

Depends

TDI cars are OBD-tested in most states with emissions programs, and the check engine light with P0272 fails that test. Heavier diesel pickups may be exempt or tested differently.

Frequently asked questions

Can a worn camshaft cause P0272?

On pump-injector TDIs, yes. The cam lobe drives the injector plunger directly, so a worn lobe reduces the fuel that cylinder gets. Common-rail engines don't have this failure because a pump builds the pressure.

What do the TDI measuring block values mean?

They show how much the computer is adding or removing per cylinder to smooth the idle. Values near zero are ideal; one cylinder near or beyond the limit tells you which one needs attention.

Does oil type really matter?

For pump-injector engines very much so. The cam and rockers see extreme loads, and oil without the right diesel approval wears them much faster.

Is P0272 the same as P0304?

No. P0304 is a misfire count on cylinder 4. P0272 says the fuel correction for cylinder 4 can't balance it, which can happen long before a true misfire.

Sources