Cylinder 2 fuel injector leaking, sticking open or delivering too much fuel; Injector electrical fault, such as a damaged wire, poor connector contact or a driver fault in the control unit; Restricted air flow into cylinder 2, for example intake valve or port deposits; Misfire on cylinder 2 from a worn spark plug, faulty coil or low compression, upsetting the mixture reading; Faulty or contaminated exhaust oxygen or air-fuel sensor giving a false rich signal; Excess fuel pressure or a fuel system fault, which usually affects more than one cylinder; Outdated or faulty engine control unit software, where the manufacturer lists it as a known cause for the model.

P029F

Cylinder 2 - Fuel Trim at Min Limit.

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)
9F: FaultThe specific fault in that area

What it means

P029F means the engine control unit has reduced fuel to cylinder 2 as far as its individual cylinder fuel trim allows, and the cylinder is still reading richer than expected. The control unit works this out from exhaust sensor readings and cylinder balancing, so it only applies to engines that trim fuel cylinder by cylinder. How the cylinder is identified varies by engine and model.

Symptoms

Engine management light on
Rough idle or uneven running
Smell of fuel from the exhaust
Poor fuel economy
Hesitation or reduced smoothness under load
Possible misfire codes stored alongside

Possible causes

Cylinder 2 fuel injector leaking, sticking open or delivering too much fuellikely
Injector electrical fault, such as a damaged wire, poor connector contact or a driver fault in the control unitpossible
Restricted air flow into cylinder 2, for example intake valve or port depositspossible
Misfire on cylinder 2 from a worn spark plug, faulty coil or low compression, upsetting the mixture readingpossible
Faulty or contaminated exhaust oxygen or air-fuel sensor giving a false rich signalpossible
Excess fuel pressure or a fuel system fault, which usually affects more than one cylinderrare
Outdated or faulty engine control unit software, where the manufacturer lists it as a known cause for the modelrare

How to diagnose

Read all stored and pending codes and note any misfire, other fuel trim or sensor codes, then review freeze frame data for load, speed and temperature when the fault set.
Look at live data for short and long term fuel trims on all cylinders and banks to see whether only cylinder 2 is affected.
Inspect the cylinder 2 injector wiring and connector for damage, corrosion, heat damage or poor pin tension.
Check the spark plug and coil on cylinder 2, and swap the coil with another cylinder to see if the fault follows it.
Check the injector's electrical resistance and driving signal against the manufacturer specification, as the method depends on the engine.
Check fuel pressure against specification and look for fuel in the engine oil.
Run a cylinder balance or compression test, and inspect the intake port or valves for deposits where the engine allows access.
Check the exhaust sensor's live readings and wiring, and look for signs of contamination.

How to fix

Replace or professionally clean and flow-test the cylinder 2 injector if it is leaking or out of specification.
Repair damaged wiring or connectors in the injector circuit.
Fit new spark plugs or a new coil if they are causing the misfire.
Clean intake valve and port deposits using a method suited to the engine.
Replace a faulty exhaust sensor once the fault is confirmed.
Update the engine control unit software only if the manufacturer identifies it as a known cause for this model.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but book it in soon. A leaking injector or rich cylinder can wash oil from the bore, dilute the engine oil and overheat the catalytic converter, so avoid long journeys and heavy loads, and stop if misfiring becomes severe.

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