OBD Guide

U1299

Door Multiplex Control Unit Lost Communication With Climate Control Unit

U1299 is an OBD-II diagnostic trouble code meaning: Door Multiplex Control Unit Lost Communication With Climate Control Unit. Common causes: broken wires in the harness, oxidation of connector contacts. Estimated repair cost: $6–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$6–167 (est.)

Symptoms

  • Climate control does not work
  • Error on the instrument panel
  • Malfunctions of electric windows
  • Incorrect operation of automatic door functions
  • Lack of communication between blocks in diagnostics

Causes

  • Broken wires in the harness
  • Oxidation of connector contacts
  • Malfunction of the door control unit
  • Problems with the climate control module
  • Multiplex bus failure

How to Fix

  1. Check the integrity of the wiring harness between the modules
  2. Clean connector contacts
  3. Check power and ground of modules
  4. Scan other modules for communication errors
  5. Replace the faulty control unit if necessary

Related codes

FAQ

What does the U1299 code mean?

U1299 is an OBD-II diagnostic trouble code that indicates: Door Multiplex Control Unit Lost Communication With Climate Control Unit

What causes a U1299 error code?

The most common causes of U1299 include: Broken wires in the harness; Oxidation of connector contacts; Malfunction of the door control unit; Problems with the climate control module.

How do I fix a U1299 diagnostic trouble code?

To fix U1299: Check the integrity of the wiring harness between the modules. Clean connector contacts. Check power and ground of modules. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U1299?

Yes, but get it checked soon

How much does it cost to fix U1299?

The estimated repair cost for U1299 is $6–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat