B2156 BMW Fault Code

Description:

Catalytic converters must be warm before they can work properly. On a cold start the PCM provides a rich mixture to keep the cold engine running.
All that extra fuel goes into the catalytic converter. But the exhaust isn't very hot, because, ah, the engine is pretty cold. GM has employed several strategies to fire up the catalytic converter quicker and reduce cold start emissions. One way is to use a secondary air pump that pumps outside air directly into the catalytic converter.

B2156 Code Symptoms :

When you turn on the ignition, the Service Engine Soon or Check Engine B2156 light should flash briefly, indicating that the OBD system is ready to scan your vehicle for any malfunctions. After this brief flash, the light should stay off while you drive as long as no problems are detected. If so, you'll be glad to know that your vehicle is equipped with an early warning system that could save you time, money, and fuel in addition to helping protect the B2156!

Diagnosis And Repairing B2156

B2156 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 B2156 code ?

• Air fuel ratio (A/F) Sensor 1 Bank 1 harness is open or shorted
• Failures of clutch motion/travel sensors.
• Continuous oil flow to the VCT piston chamber
• Fuel injectors harness is open or shorted

Some systems require that the actuator has an adequate supply of brake fluid. Low brake fluid levels can mimic the symptoms of code B2156, so consult the manual to locate the brake fluid reservoir.

Bear in mind that a low fluid level can set code B2156 on some applications, so make sure that on fluid operated systems the fluid level is up to the mark before starting an electrical diagnosis.