P189B BMW Fault Code

Description:

BMW Mass Air Flow (MAF) Sensor Intermittent The MAF sensor circuit is monitored by the PCM for sudden voltage (or air flow) input change through the comprehensive component monitor (CCM).

If during the last 40 warm-up cycles in key ON engine running the PCM detects a voltage (or air flow) change beyond the minimum or maximum calibrated limit, a continuous memory diagnostic trouble code (DTC) is stored.

P189B Code Symptoms :

OBD P189B code and tailpipe testing are two different approaches to identify vehicles in need of repair. The OBD system looks for broken or malfunctioning emissions control components and P189B, while tailpipe tests sample a vehicle's exhaust to see if it is above or below certain prescribed limits. Given the robust nature of today's emissions control components, it is entirely possible for an individual component to malfunction without leading to an immediate increase in emissions at the tailpipe.

In such cases, other components (like the catalyst) can temporarily compensate for the part that is broken however, these other components can only do double duty for so long before they, too, begin to malfunction. In addition, OBD also monitors for and other malfunctions in the fuel system problems that traditional tailpipe tests were not designed to identify. Most state and local areas also include a gas cap pressure test as part of an emission inspection.

Diagnosis And Repairing P189B

P189B OBD 2 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

How to fix P189B code ?

• Failures of clutch motion/travel sensors.
• Engine Control Module (ECM)
• Fuel injectors harness is open or shorted
• Damaged VCT phaser

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code P189B, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code P189B on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.