What Does P02B9 Mean?
The ECM has detected that the fuel injector on cylinder 8 is leaking fuel, allowing unmetered fuel to enter the combustion chamber when the injector should be fully closed. This produces an overly rich condition on cylinder 8 with incomplete combustion. The driver may notice rough idle, black exhaust smoke, fuel odor, poor fuel economy, and cylinder 8 misfires.
Common Causes
35%
Worn or damaged injector pintle seal or O-ring allowing fuel seepage when the injector is commanded closed
25%
Cracked or scored injector nozzle seat preventing complete fuel shutoff
20%
Contaminated or corroded injector internals causing the needle valve to stick partially open
12%
Excessive fuel system pressure forcing fuel past the injector seal during closed periods
8%
Faulty injector driver circuit holding the injector partially energized
Diagnostic Steps
1
Monitor cylinder 8 short-term and long-term fuel trim values — a significantly negative trim (below -10%) confirms the ECM is compensating for a rich condition from the injector leak.
2
Perform a fuel injector balance test or cylinder power contribution test to compare cylinder 8 against the other cylinders.
3
Check fuel system pressure: key-on engine-off should hold at specified rail pressure (typically 55-62 PSI). Monitor bleed-down rate after shutoff.
4
Remove the fuel rail with injectors (engine off, pressure relieved) and apply regulated pressure while observing each injector tip — no more than 1 drop per minute is acceptable.
5
Inspect the cylinder 8 spark plug for heavy black carbon fouling or wet fuel deposits confirming unmetered fuel entry.
Estimated Repair Cost
$150 - $450
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel injector on cylinder 8 is leaking fuel, allowing unmetered fuel to enter the combustion chamber when the injector should be fully closed. This produces an overly rich condition on cylinder 8 with incomplete combustion. The driver may notice rough idle, black exhaus...
The most common cause of P02B9 (Cylinder 8 - Injector Leaking) is: Worn or damaged injector pintle seal or O-ring allowing fuel seepage when the injector is commanded closed
Typical repair costs for P02B9 range from $150 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Driveable short distances but repair soon. A leaking injector washes oil from cylinder walls causing wear, overloads the catalytic converter, and in severe cases creates a fire hazard from raw fuel in the exhaust.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02B9 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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