What Does P029D Mean?
The ECM has detected that the fuel injector on cylinder 1 is leaking fuel into the combustion chamber when it should be closed. This is determined through individual cylinder fuel trim analysis, where cylinder 1 consistently requires maximum negative (lean) fuel correction because it is receiving too much fuel. The driver may notice rough idle, black smoke, fuel odor from the exhaust, or a fouled spark plug on cylinder 1.
Common Causes
40%
Worn or damaged injector pintle seal allowing fuel to seep past when the injector is commanded closed
25%
Carbon or debris lodged in the injector tip preventing complete closure of the injector valve
15%
Injector return spring weakened or broken, failing to close the valve fully against fuel pressure
12%
Excessive fuel system pressure forcing fuel past a marginally sealing injector
8%
Electrical issue holding the injector partially energized when it should be off
Diagnostic Steps
1
Perform a fuel injector leak-down test: pressurize the fuel rail to operating pressure with the engine off, remove spark plugs, and inspect cylinder 1 for fuel dripping into the bore over 10-15 minutes. Maximum allowable leakage is typically one drop per minute.
2
Remove the cylinder 1 spark plug and compare it to other cylinders; a black, wet, fuel-fouled plug confirms over-fueling on that cylinder.
3
Monitor cylinder 1 individual fuel trim with the scan tool; confirm it is pegged at the maximum negative correction limit.
4
Remove the cylinder 1 injector and test on a flow bench for static leak rate (fuel flow with injector de-energized); any measurable flow confirms the leak.
5
Check fuel system pressure with a gauge; verify it is within spec (typically 35-65 psi). Excessive pressure can worsen an injector leak.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel injector on cylinder 1 is leaking fuel into the combustion chamber when it should be closed. This is determined through individual cylinder fuel trim analysis, where cylinder 1 consistently requires maximum negative (lean) fuel correction because it is receiving to...
The most common cause of P029D (Cylinder 1 - Injector Leaking) is: Worn or damaged injector pintle seal allowing fuel to seep past when the injector is commanded closed
Typical repair costs for P029D range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A leaking injector creates a fire risk if fuel accumulates in the intake manifold or engine bay. It also washes lubricating oil from the cylinder wall, accelerating wear, and can cause hydro-lock on startup in severe cases. Repair promptly; avoid letting the vehicle sit for extended periods with fuel pressure up.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P029D to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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