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DTC codes / P02xx · Fuel and air metering (injector circuits) / P02AD

P02ADCylinder 5 - Injector Leaking

P02AD indicates that the engine control module has detected a leaking fuel injector on cylinder 5, typically by monitoring fuel trim or oxygen sensor feedback and seeing an overly rich condition that cannot be corrected. The computer recognizes that cylinder 5 is receiving more fuel than commanded, which can lead to rough running, misfires, and increased emissions.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Rough idle or engine misfire, especially noticeable at stoplights
  • Strong fuel odor from the exhaust or engine bay
  • Black smoke from the tailpipe
  • Decreased fuel economy
  • Often no symptoms besides the warning light, especially in early stages
  • Engine may run rough or stall after startup

Common causes, most likely first

  1. Faulty fuel injector on cylinder 5 that is stuck open or leaking internally
  2. Worn or damaged injector O-rings or seals allowing fuel to seep past
  3. Contaminated fuel or debris causing the injector needle to not seat properly
  4. Electrical issue such as a short to power in the injector control circuit keeping the injector energized
  5. Mechanical damage to the injector nozzle or body
  6. High fuel pressure from a faulty pressure regulator or restricted return line
  7. Engine control module software or hardware fault incorrectly commanding the injector

How to diagnose and fix it

  1. Perform a visual inspection of the cylinder 5 injector and its electrical connector for damage or fuel leaks
  2. Use a scan tool to check fuel trim values and compare cylinder 5 contribution with other cylinders
  3. Conduct an injector balance test or cylinder contribution test to confirm the leaking injector
  4. Check fuel pressure with a gauge to rule out excessive system pressure
  5. Remove and inspect the cylinder 5 injector for signs of leakage or damage, and test it on a bench if possible
  6. Replace the faulty fuel injector and any damaged seals or O-rings, following manufacturer procedures
  7. Clear the diagnostic trouble codes and verify the repair with a road test and fuel trim readings

Before you replace that injector

  • A leaking injector can sometimes be caused by a faulty engine control module driver that keeps the injector energized, so always check for a short to power in the control circuit before condemning the injector.
  • Fuel contamination from a recent fill-up at a station with dirty tanks is a common cause that many technicians overlook, so inspect the fuel for debris or water.
  • The code may set intermittently if the leak is small, and a simple fuel pressure leak-down test can reveal a leaking injector even when the code is not currently active.
  • A stuck-open injector can wash down the cylinder wall, leading to premature wear and oil dilution, so address the issue promptly to avoid engine damage.
  • Replacing just the leaking injector without checking fuel pressure and the entire fuel system may lead to repeat failures if the root cause is excessive pressure or contamination.

Can I keep driving with P02AD?

It is not advisable to continue driving with a leaking injector for an extended period, as it can cause catalytic converter damage and engine wear. If the check engine light is on but the engine runs smoothly, you may drive cautiously to a repair shop, but avoid heavy acceleration or long trips.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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