What Does P02B3 Mean?
The ECM has detected that the individual fuel trim correction for cylinder 7 has reached its minimum limit. The system is subtracting the maximum possible fuel from cylinder 7 but still detects an overly rich condition. This means cylinder 7 is receiving substantially more fuel than commanded, and the ECM has exhausted its correction range. The driver may notice rough running, black smoke, poor fuel economy, and strong fuel odor.
Common Causes
35%
Leaking cylinder 7 fuel injector allowing excess fuel into the combustion chamber when it should be sealed
20%
Faulty injector driver circuit or ECM holding the cylinder 7 injector energized longer than commanded
20%
Carbon buildup on cylinder 7 intake valve (GDI engines) causing poor atomization and incomplete combustion
15%
Low compression on cylinder 7 causing incomplete combustion and unburned fuel entering the exhaust
10%
Contaminated engine oil diluted with fuel affecting bank-level O2 sensor readings
Diagnostic Steps
1
Review live data for cylinder 7 individual fuel trim — confirm it is at or near the maximum negative correction limit (typically -25% to -30%).
2
Perform a relative compression test via cranking RPM analysis to verify cylinder 7 has adequate compression — a weak cylinder produces poor combustion that appears as a rich condition.
3
Remove and inspect the cylinder 7 spark plug for heavy black carbon fouling or wet fuel deposits confirming excess fuel.
4
With the fuel rail removed, apply regulated fuel pressure and observe the cylinder 7 injector tip for dripping — no more than 1 drop per minute is acceptable.
5
Check the cylinder 7 injector wiring for short circuits to ground or power, and verify injector resistance matches specifications (typically 11-17 ohms).
Estimated Repair Cost
$150 - $500
Parts + labor, varies by vehicle and location
The ECM has detected that the individual fuel trim correction for cylinder 7 has reached its minimum limit. The system is subtracting the maximum possible fuel from cylinder 7 but still detects an overly rich condition. This means cylinder 7 is receiving substantially more fuel than commanded, and t...
The most common cause of P02B3 (Cylinder 7 - Fuel Trim at Min Limit) is: Leaking cylinder 7 fuel injector allowing excess fuel into the combustion chamber when it should be sealed
Typical repair costs for P02B3 range from $150 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle can be driven short distances but should be repaired promptly. An overly rich cylinder 7 washes oil from the cylinder walls, accelerates catalytic converter damage, and in severe cases creates a fire hazard from raw fuel in the exhaust system.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02B3 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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