P2189 trouble code definition
The most environmentally friendly and power efficient air-fuel ratio for gasoline engines that we modernly know is 14.7:1. The engine control module (ECM) is programmed to adjust things like fuel delivery and ignition timing if needed to keep the air-fuel ratio at or near the 14.7:1 ratio. Trouble code P2189 indicates that the ECM has determined that there is too much air and too little fuel present in the air-fuel ratio during engine idle.
What the P2189 code means
This code indicates that during the last two drive cycles, the ECM has observed a lean air-fuel ratio condition on bank 2 of the engine. The manufacture designed the ECM with the ability to adjust the air-fuel ratio by changing the ignition timing and fuel injection pulse width to help achieve 14.7:1. The ECM can only adjust the air-fuel ratio to a certain extent. If the margin of adjustment is too wide for the ECM to correct the lean condition, then a code P2189 will set.
What causes the P2189 code?
- Faulty EVAP system purge valve
- Vacuum leak
- Faulty crankcase ventilation valve
- Leaking crankcase ventilation valve grommet
- Leaking intake manifold gaskets
- Loose intake manifold
- Faulty bank 2 oxygen sensor
- Fuel pressure low due to weak fuel pump
- Restricted fuel supply such as pinched fuel line or clogged fuel filter
- Air intake leak
- Loose oil cap
- Faulty gas cap seal
- Leaks in the exhaust system
- Mechanical issue in one or more of the bank 2 fuel injectors
- Faulty manifold absolute pressure sensor
- Faulty fuel pressure regulator
What are the symptoms of the P2189 code?
- Check Engine Light illumination
- Misfire at idle
- Engine hesitation
- Engine hard to start, especially when warm
- Whistling noises coming from the engine area
How does a mechanic diagnose the P2189 code?
- Performing a fuel pressure test
- Performing a fuel injector flow test
- Inspecting the EVAP system for leaks
- Inspecting the intake manifold for leaks
- Inspecting the air intake and vacuum lines for leaks
- Inspecting the crankcase ventilation grommet for leaks
- Inspecting the rubber seal of the gas cap
- Performing an inspection of the exhaust system
- Using a scan tool to view the long and short-term fuel ratio
- Using a scan tool to view the oxygen sensor live data
Common mistakes when diagnosing the P2189 code
Often times, a mechanic may not check the vacuum lines and EVAP system of the vehicle. The EVAP system and vacuum lines are among one of the most likely things to cause a lean condition.
How serious is the P2189 code?
It is fairly serious because an improper air-fuel ratio will generate excessive emissions, which will cause harm to the environment.
What repairs can fix the P2189 code?
- Repair of a leaking air intake
- Replacement of a faulty gas cap seal
- Repair or replacement of leaking exhaust system components
- Repairing a mechanical issue in one or more of the bank 2 fuel injectors
- Replacement of a faulty manifold absolute pressure sensor
- Replacement of a faulty fuel pressure regulator
- Replacement of a faulty EVAP system purge valve
- Repair of a vacuum leak(s)
- Replacement of faulty crankcase ventilation valve and grommet
- Replacement of leaking intake manifold gaskets
- Tightening the intake manifold bolts
- Replacement of a faulty oxygen sensor
- Replacement of weak fuel pump
- Replacement of a faulty or clogged fuel filter
- Replacement of a pinched fuel line
Additional comments for consideration regarding the P2189 code
As there are many components which can cause this code, it is recommended to have an experienced technician point out the faulted component through proper testing and inspection to save time and money.
Need help with a P2187 code?
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