What Does P02AD Mean?
The ECM has detected that the fuel injector on cylinder 5 is leaking fuel, permitting unmetered fuel to enter the combustion chamber or intake manifold when the injector should be fully closed. This causes an overly rich condition on that specific cylinder, resulting in incomplete combustion. The driver may notice rough idle, black exhaust smoke, fuel odor, poor fuel economy, and possible misfires on cylinder 5.
Common Causes
35%
Worn or damaged injector pintle seal or O-ring allowing fuel seepage past the injector tip when closed
25%
Cracked or scored injector nozzle seat preventing full shutoff of fuel flow
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 5 short-term and long-term fuel trim values via live data — a significantly negative fuel trim (below -10%) on that cylinder confirms the ECM is compensating for a rich condition caused by the leak.
2
Perform a fuel injector balance test or cylinder power contribution test to compare cylinder 5's contribution against the other cylinders.
3
Check fuel system pressure with a gauge: key-on engine-off should hold at the specified rail pressure (typically 55-62 PSI). Monitor pressure bleed-down rate after shutoff — rapid decay indicates a leaking injector or check valve.
4
Remove the fuel rail with injectors attached (engine off, pressure relieved) and apply regulated fuel pressure while observing each injector tip for dripping — cylinder 5's injector should hold with no more than 1 drop per minute.
5
Inspect the cylinder 5 spark plug for heavy black carbon fouling or wet fuel deposits confirming fuel is entering the cylinder unmetered.
Estimated Repair Cost
$150 - $450
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel injector on cylinder 5 is leaking fuel, permitting unmetered fuel to enter the combustion chamber or intake manifold when the injector should be fully closed. This causes an overly rich condition on that specific cylinder, resulting in incomplete combustion. The dr...
The most common cause of P02AD (Cylinder 5 - Injector Leaking) is: Worn or damaged injector pintle seal or O-ring allowing fuel seepage past the injector tip when closed
Typical repair costs for P02AD range from $150 to $450, 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 soon. A leaking injector washes cylinder walls of protective oil, causing accelerated wear, and excess fuel can overheat and damage the catalytic converter. In severe cases, raw fuel in the exhaust creates a fire risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P02AD to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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