U0103: Lost communication with the gear shift module

What U0103 means

The car’s control units talk to each other over a data network (CAN bus). This code means the module that reads the gear lever position has stopped sending messages. Without that information, the gearbox may not know which gear you have selected.

Most common causes

• Low battery or loose terminals, especially after a jump start or battery change
• Blown fuse for the gear selector module
• Loose, corroded or damp connector on the module
• Poor ground connection to the module
• Damaged or chafed network wiring under the centre console
• Faulty gear selector module

Symptoms

• Engine or gearbox warning light on
• Gearbox ignores the lever or will not leave Park
• Gear indicator on the dashboard blank or flashing
• Gearbox goes into limp mode

Can you drive with U0103?

With care If the gearbox responds normally you can drive, but it may stick in one gear or refuse to leave Park. Get it checked soon.

How to check it

Check which other U codes are stored: if several modules have lost communication, the problem is usually power supply or the network rather than this module. Also measure battery voltage with the engine off (around 12.4 V or more).

How to read and clear U0103 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see U0103 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

• U0100 Lost communication with engine control module (ECM/PCM A)
• U0101 Lost communication with transmission control module (TCM)
• U0102 Lost communication with transfer case control module
• U0104 Lost communication with the cruise control module
• U0107 Lost communication with the throttle actuator control module
• U0121 Lost communication with the ABS control module
• U0126 Lost communication with the steering angle sensor module
• U0128 Lost communication with the park brake control module
• U0131 Lost communication with the power steering control module
• U0140 Lost communication with the body control module (BCM)
• U0141 Lost communication with body control module A

U0103 is a generic code, so it means the same on any make, for example on Alfa Romeo, Cupra, Dacia, Jeep, Nissan, Škoda. See what Final OBD does on your car in makes and models.