OBD Guide

U029D

Lost Communication With NOx Sensor A

U029D is an OBD-II diagnostic trouble code meaning: Lost Communication With NOx Sensor A. Common causes: nox sensor a fault, open or short circuit in the sensor circuit. Estimated repair cost: $167–444.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$167–444 (est.)

Symptoms

  • Check Engine light comes on
  • Reduced engine power
  • Increased fuel consumption
  • Problems with passing environmental tests
  • Possible SCR system error messages

Causes

  • NOx sensor A fault
  • Open or short circuit in the sensor circuit
  • Damaged or oxidized connectors
  • Sensor power problems
  • Engine control unit malfunction

How to Fix

  1. Check the integrity of the NOx sensor wiring and connectors
  2. Check the power supply and ground of the sensor
  3. Read sensor parameters via diagnostic scanner
  4. If necessary, replace NOx sensor A
  5. Check and update ECU software if necessary

Related codes

Error U029D by Vehicle Brand

FAQ

What does the U029D code mean?

U029D is an OBD-II diagnostic trouble code that indicates: Lost Communication With NOx Sensor A

What causes a U029D error code?

The most common causes of U029D include: NOx sensor A fault; Open or short circuit in the sensor circuit; Damaged or oxidized connectors; Sensor power problems.

How do I fix a U029D diagnostic trouble code?

To fix U029D: Check the integrity of the NOx sensor wiring and connectors. Check the power supply and ground of the sensor. Read sensor parameters via diagnostic scanner. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with U029D?

Yes, but get it checked soon

How much does it cost to fix U029D?

The estimated repair cost for U029D is $167–444. Actual cost depends on your vehicle, location, and labor rates.

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