What Does P02A2 Mean?
The ECM has detected that the individual cylinder fuel trim for cylinder 3 has reached its maximum enrichment limit. The ECM is adding the maximum possible extra fuel to cylinder 3, but the air/fuel mixture remains too lean. This indicates a cylinder-specific lean condition on cylinder 3 that could stem from an air leak, restricted injector, or exhaust leak near that cylinder. The driver may notice rough idle, hesitation, or a misfire.
Common Causes
35%
Vacuum leak at the cylinder 3 intake port, runner gasket, or adjacent vacuum hose
30%
Partially clogged cylinder 3 fuel injector delivering less fuel than commanded
15%
Exhaust leak near the cylinder 3 exhaust port introducing ambient air and causing a false lean reading
12%
Low fuel system pressure affecting fuel delivery to cylinder 3
8%
Cylinder 3 compression issue causing poor combustion and lean exhaust readings
Diagnostic Steps
1
Monitor cylinder 3 individual fuel trim via the scan tool; verify it is at or near the positive enrichment limit (typically +25% to +30%).
2
Perform an intake manifold smoke test with emphasis on the cylinder 3 intake runner and port gasket surfaces; watch for smoke leaking from joints, cracks, or vacuum fittings.
3
Test cylinder 3 injector delivery via an injector balance test (disable each injector and compare RPM drops); a smaller RPM drop on cylinder 3 suggests restricted fuel flow.
4
Measure fuel pressure at the rail with a gauge during idle and under load; pressure should be within manufacturer specification and remain stable.
5
Inspect the exhaust manifold near cylinder 3 for cracks or gasket failure; at cold startup, listen and feel for exhaust pulses escaping at the 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 3 has reached its maximum enrichment limit. The ECM is adding the maximum possible extra fuel to cylinder 3, but the air/fuel mixture remains too lean. This indicates a cylinder-specific lean condition on cylinder 3 that could ...
The most common cause of P02A2 (Cylinder 3 - Fuel Trim at Max Limit) is: Vacuum leak at the cylinder 3 intake port, runner gasket, or adjacent vacuum hose
Typical repair costs for P02A2 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 at reduced load. A lean condition on cylinder 3 raises exhaust temperatures and can damage the catalytic converter over time. If misfiring is noticeable at highway speeds, the catalytic converter overheating risk increases significantly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02A2 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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