B0138 BMW Fault Code

Description:

The input turbine speed sensor detects rotation of the input shaft of the input shaft speed sensor transmission. The computer uses that information, along with the output shaft speed sensor to determine if the transmission is operating according to plan. If the computer detects a difference between the input shaft speed , and the expected output shaft speed, it will adjust transmission pump pressure to prevent clutch disc slip. If adding pressure doesn't solve the problem, it will set a trouble code.

B0138 Code Symptoms :

While fuel economy was increased, acceleration was seriously compromised, and the loss of engine vacuum led to a dangerous loss of braking assist when the B0138 code system was in four-cylinder mode. In addition to these issues, while the company proposed a hydraulically controlled system that could be switched from within the car, the version they implemented had to be manually changed in the engine compartment using hand tools.

Diagnosis And Repairing B0138

Parts or components should not be replaced with reference to only a B0138 DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.

How to fix B0138 code ?

• Damaged VCT phaser
• Faulty Crankshaft Position Sensor (POS)
• Faulty Air fuel ratio (A/F) Sensor 1 Bank 1
• Clogged or faulty fuel injector (s)

On some transmissions, such as automated manual transmissions or automatic transmissions with manual mode, the GSP switch lets the TCM know whether or not the driver has selected automatic or manual function.

On manual transmissions, the GSP switch informs the TCM which gear the driver is selecting, and may function as a neutral safety switch, depending on system design. The TCM also uses the gate select position switch to monitor transmission operation. For example, if the driver selects manual mode and selects 3rd gear on an automatic transmission, the TCM may monitor speed sensors to detect clutch and brake slippage.