What Does P029F Mean?
The ECM has detected that the individual cylinder fuel trim for cylinder 2 has reached its minimum limit, meaning the ECM is subtracting the maximum allowable amount of fuel from cylinder 2 but the mixture is still too rich. This indicates an over-fueling condition on cylinder 2 that the fuel management system cannot fully compensate for. Symptoms include rough idle, black smoke, fuel odor, and potentially a fouled spark plug on cylinder 2.
Common Causes
35%
Leaking cylinder 2 fuel injector dripping fuel into the combustion chamber when commanded off
20%
Cylinder 2 ignition failure (weak coil or fouled spark plug) causing incomplete combustion and rich exhaust
20%
Carbon deposits on cylinder 2 intake valve affecting fuel atomization (port-injected engines)
15%
Incorrect or wrong-specification injector installed on cylinder 2 with higher flow rating
10%
Low compression on cylinder 2 causing inefficient combustion and rich exhaust signature
Diagnostic Steps
1
Monitor cylinder 2 individual fuel trim; confirm it is at or near the maximum negative (lean correction) limit, typically -25% to -30%.
2
Perform a fuel injector leak-down test by pressurizing the fuel rail with the engine off and inspecting cylinder 2 for fuel dripping into the bore via the spark plug hole.
3
Remove and compare the cylinder 2 spark plug to other cylinders; a black, wet, carbon-fouled plug confirms rich running on that specific cylinder.
4
Test cylinder 2 ignition coil output with a spark tester; verify strong, consistent spark. A weak spark causes incomplete combustion that appears as a rich condition.
5
Measure cylinder 2 compression and compare to other cylinders; low compression causes poor burn efficiency. Variation exceeding 10-15% warrants further investigation.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The ECM has detected that the individual cylinder fuel trim for cylinder 2 has reached its minimum limit, meaning the ECM is subtracting the maximum allowable amount of fuel from cylinder 2 but the mixture is still too rich. This indicates an over-fueling condition on cylinder 2 that the fuel manage...
The most common cause of P029F (Cylinder 2 - Fuel Trim at Min Limit) is: Leaking cylinder 2 fuel injector dripping fuel into the combustion chamber when commanded off
Typical repair costs for P029F range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Driving is possible for short distances but the rich condition on cylinder 2 will foul the spark plug, wash oil from the cylinder wall, and contaminate the catalytic converter over time. Prolonged driving risks catalytic converter failure and increased fuel consumption.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P029F to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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