What Does P02B4 Mean?
The ECM has detected that the fuel injector on cylinder 7 is restricted, meaning fuel delivery is reduced below the commanded amount due to partial blockage or diminished flow capacity. The ECM identifies this through individual cylinder fuel trim corrections consistently showing the injector is underperforming. The driver may experience cylinder 7 misfires, hesitation, rough idle, and noticeable power loss.
Common Causes
40%
Clogged injector filter basket or nozzle tip from fuel contaminants, varnish deposits, or carbon buildup
25%
Internal injector deposits from low-quality fuel or ethanol partially blocking the spray orifices
15%
Kinked or pinched fuel supply line reducing flow to the rail
12%
Clogged in-line fuel filter or pump strainer reducing overall fuel system pressure and flow volume
8%
Corroded or damaged injector electrical connector causing intermittent operation that mimics a restriction
Diagnostic Steps
1
Check live data for cylinder 7 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 7 should produce a similar drop as the others. A smaller drop indicates reduced flow.
3
Remove the fuel injectors for professional flow testing and ultrasonic cleaning — measure actual flow rate versus specification and compare to other injectors. Variation should be less than 5%.
4
Inspect the fuel rail for debris or contamination by examining injector seats and fuel passages for deposits or corrosion.
5
Verify fuel system pressure at idle and under load to rule out a supply-side restriction affecting overall fuel delivery.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel injector on cylinder 7 is restricted, meaning fuel delivery is reduced below the commanded amount due to partial blockage or diminished flow capacity. The ECM identifies this through individual cylinder fuel trim corrections consistently showing the injector is und...
The most common cause of P02B4 (Cylinder 7 - Injector Restricted) is: Clogged injector filter basket or nozzle tip from fuel contaminants, varnish deposits, or carbon buildup
Typical repair costs for P02B4 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, but the lean condition on cylinder 7 produces elevated combustion temperatures that risk catalytic converter damage. Extended driving risks misfire-induced catalyst overheating and lean detonation damage to the piston.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02B4 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
