P2189 - SYSTEM TOO LEAN AT IDLE BANK 2

The ECM (Engine Control Module) is programmed to adjust the fuel delivery and ignition timing to keep the air/fuel mixture as close to the stoichiometric ratio as possible. This ratio is environmentally friendly and provides better engine performance.

P2189 OBDII diagnostic code indicates that the ECM has encountered a problem in the fuel mixture, in idle mode. In this case, the mixture is excessively lean at idle. This code is set for bank 2.

How does the P2189 Generic Fault Code work?

This DTC is a generic transmission code. It is deemed universal, as it appears to be applicable to all brands and models of vehicles (1996 and later), although the actual repair steps may differ slightly depending on the model.

This is an unclear code in itself. This code is tricky to troubleshoot without a good diagnosis approach. Between the last two startups, the ECM senses trouble with the idle fuel mixture. Then it seems that the fuel mixture is too lean (too much air and not enough fuel) at idle.

There is an exhaustive list of possible components that can put you in this situation. The diagnostic steps are simple for the most part: it just takes a long time unless it is checked first. The approach calls for observing and noting controllability problems, starting with the most usual troubles and continuing.

You should also know that at first glance, this code is almost identical to P2187. The main difference is that P2187 addresses block 1 (the side of the engine containing cylinder #1) and P2189 addresses block 2.

• Check Engine light illuminated.
• Difficulty starting the vehicle.
• Strong fuel odor.
• Other fault codes are stored.

Your approach to tracking down this fault starts with a test drive and looking for any symptoms. The next move is to use a code scanner ( which is available at any auto parts store) and obtain supplemental codes.

The computer has set the P2189 code to denote that the fuel mixture is lean at idle. This is the basic code, however, any faulty components in this cycle could cause a lean mixture that will also be set in the code. If the test drive shows no symptoms, it might not be the actual code. In other words, the fuel mixture is not lean and the computer or oxygen sensor is the real one responsible for setting the code.

The causes of the P2189 OBD2 fault code are:

• Maybe the Fuel Tank Cap is not tightened properly or is defective.
• The Oxygen Sensor in front of the Catalyst may be defective.
• There may be air leaks near the Mass Air Flow (MAF) Sensor due to cracked hoses or vacuum lines.
• The Manifold Absolute Pressure (MAP) sensor could be defective.
• A fuel injector could be leaking.
• The fuel pressure regulator may be bad.