What Does P02B8 Mean?
The ECM has detected that the fuel injector on cylinder 8 is restricted, meaning it cannot deliver the commanded amount of fuel due to partial blockage or diminished flow. The system identifies this through persistent positive individual fuel trim corrections for that cylinder. The driver may experience cylinder 8 misfires, hesitation, rough idle, and reduced engine power output.
Common Causes
40%
Clogged injector filter basket or nozzle tip from fuel contaminants, varnish, or carbon deposits
25%
Internal injector deposits from poor-quality fuel or ethanol partially blocking spray orifices
15%
Kinked or pinched fuel supply line reducing fuel flow to the rail
12%
Clogged in-line fuel filter or pump strainer reducing overall system fuel pressure and volume
8%
Corroded or damaged injector electrical connector causing intermittent operation that mimics restriction
Diagnostic Steps
1
Check live data for cylinder 8 individual fuel trim — a high positive trim value confirms the ECM is compensating for reduced fuel delivery.
2
Perform an injector balance test by disabling each injector and monitoring rpm drops — cylinder 8 should produce a similar drop as others.
3
Remove fuel injectors for professional flow testing and ultrasonic cleaning — measure actual flow rate versus specification. Variation between injectors should be less than 5%.
4
Inspect the fuel rail for debris or contamination at injector seats and fuel passages.
5
Verify fuel system pressure at idle and under load to rule out a supply-side restriction.
6
On V8 engines, check the fuel rail balance tube or crossover for any restrictions that could starve the rear-bank injectors.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel injector on cylinder 8 is restricted, meaning it cannot deliver the commanded amount of fuel due to partial blockage or diminished flow. The system identifies this through persistent positive individual fuel trim corrections for that cylinder. The driver may experi...
The most common cause of P02B8 (Cylinder 8 - Injector Restricted) is: Clogged injector filter basket or nozzle tip from fuel contaminants, varnish, or carbon deposits
Typical repair costs for P02B8 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Generally safe for short-distance driving. The lean condition on cylinder 8 produces elevated combustion temperatures that risk catalytic converter damage over time and can lead to lean detonation if not addressed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02B8 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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