What Does P02D3 Mean?
The ECM has detected that Cylinder 4 fuel injector offset learning correction has reached its maximum allowable limit. The PCM is adding the maximum permissible fuel to Cylinder 4 but cannot compensate for the under-fueling condition. Cylinder 4 is delivering less fuel than commanded, suggesting a restricted injector, weak solenoid, or localized lean condition.
Common Causes
40%
Partially clogged Cylinder 4 fuel injector with internal deposits restricting fuel flow below adaptive correction range
25%
Degraded Cylinder 4 injector solenoid coil with elevated resistance causing reduced pintle lift and flow
20%
Low fuel system pressure from weak fuel pump or restricted filter disproportionately affecting Cylinder 4
15%
Vacuum leak at Cylinder 4 intake runner or gasket causing localized lean air/fuel ratio
Diagnostic Steps
1
Step 1: Review injector offset learning values for all cylinders. A strongly positive Cylinder 4 offset confirms under-fueling relative to other cylinders.
2
Step 2: Perform an injector flow bench test or in-vehicle balance test to compare Cylinder 4 flow against the other injectors. Deviation greater than 5% is considered out of specification.
3
Step 3: Swap Cylinder 4 injector with an adjacent cylinder, clear learned values, and drive through a relearn cycle. If the lean bias follows the injector, replace or professionally clean it.
4
Step 4: Smoke test the intake manifold area around Cylinder 4 for vacuum leaks, paying attention to runner gaskets, PCV connections, and brake booster hoses in that area.
5
Step 5: Verify fuel pump pressure and volume delivery at idle and under wide-open throttle. Confirm the fuel filter is not restricted by checking pressure drop across it.
Estimated Repair Cost
$150 - $650
Parts + labor, varies by vehicle and location
The ECM has detected that Cylinder 4 fuel injector offset learning correction has reached its maximum allowable limit. The PCM is adding the maximum permissible fuel to Cylinder 4 but cannot compensate for the under-fueling condition. Cylinder 4 is delivering less fuel than commanded, suggesting a r...
The most common cause of P02D3 (Cylinder 4 Fuel Injector Offset Learning At Max Limit) is: Partially clogged Cylinder 4 fuel injector with internal deposits restricting fuel flow below adaptive correction range
Typical repair costs for P02D3 range from $150 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Under-fueling creates lean misfires that increase exhaust temperatures, risk catalytic converter damage, and cause noticeable drivability symptoms including hesitation and rough idle.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02D3 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
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