What Does P029E Mean?
The ECM has detected that the individual cylinder fuel trim for cylinder 2 has reached its maximum enrichment limit. The ECM is adding the maximum allowable extra fuel to cylinder 2, but the air/fuel ratio remains too lean. This points to a cylinder-specific lean condition on cylinder 2 such as a vacuum leak, restricted injector, or exhaust leak near that cylinder. The driver may experience rough idle, intermittent misfire, or hesitation.
Common Causes
35%
Vacuum leak at the cylinder 2 intake runner, port gasket, or nearby vacuum hose allowing unmetered air
30%
Partially restricted cylinder 2 fuel injector reducing fuel delivery below the commanded amount
15%
Exhaust leak at the cylinder 2 exhaust port or manifold gasket causing a false lean O2 reading
12%
Low fuel system pressure from a weak pump or clogged filter disproportionately affecting cylinder 2
8%
Cylinder 2 compression issue causing poor combustion and lean exhaust signature
Diagnostic Steps
1
Monitor cylinder 2 individual fuel trim via the scan tool; verify it is at the maximum positive (enrichment) limit, typically +25% to +30%.
2
Perform an intake manifold smoke test focusing on the cylinder 2 intake runner and port area; look for smoke escaping from gasket surfaces or vacuum connections near that cylinder.
3
Test cylinder 2 injector by performing an injector balance test (disable each injector individually and compare RPM drops); a significantly smaller RPM drop on cylinder 2 indicates under-fueling.
4
Check fuel pressure at the rail with a gauge during idle and snap throttle; pressure should remain steady within specification. A drop under load indicates fuel supply issues.
5
Inspect the exhaust manifold at cylinder 2 for cracks or a blown gasket by starting the engine cold and listening/feeling for exhaust pulses at the gasket flange.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The ECM has detected that the individual cylinder fuel trim for cylinder 2 has reached its maximum enrichment limit. The ECM is adding the maximum allowable extra fuel to cylinder 2, but the air/fuel ratio remains too lean. This points to a cylinder-specific lean condition on cylinder 2 such as a va...
The most common cause of P029E (Cylinder 2 - Fuel Trim at Max Limit) is: Vacuum leak at the cylinder 2 intake runner, port gasket, or nearby vacuum hose allowing unmetered air
Typical repair costs for P029E range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Short-distance driving is acceptable. A lean-running cylinder 2 elevates exhaust temperature and can overheat the catalytic converter. If misfiring occurs at speed, unburned air entering the exhaust can cause catalytic converter damage or glow. Repair within a few days.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P029E 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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