OBD Guide
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P1129

Downstream Oxygen Sensors Swapped from Bank to Bank

P1129 is an OBD-II diagnostic trouble code meaning: Downstream Oxygen Sensors Swapped from Bank to Bank. Common causes: incorrect connection of oxygen sensors after repair, wiring damage. Estimated repair cost: $22–56.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$22–56 (est.)

Symptoms

  • Unstable engine operation
  • Increased fuel consumption
  • Increased emissions
  • Check Engine Light Is On

Causes

  • Incorrect connection of oxygen sensors after repair
  • Wiring damage
  • Error when replacing sensors
  • Engine control unit malfunction

How to Fix

  1. Check that the oxygen sensors are connected correctly
  2. Inspect the wiring for damage
  3. Check the operation of oxygen sensors
  4. Replace sensors if necessary

Related codes

P1130P1131P1132

Error P1129 by Vehicle Brand

AcuraFordHondaInfinitiLexusLincolnMazdaMercuryToyotaVolkswagen

FAQ

What does the P1129 code mean?

P1129 is an OBD-II diagnostic trouble code that indicates: Downstream Oxygen Sensors Swapped from Bank to Bank

What causes a P1129 error code?

The most common causes of P1129 include: Incorrect connection of oxygen sensors after repair; Wiring damage; Error when replacing sensors; Engine control unit malfunction.

How do I fix a P1129 diagnostic trouble code?

To fix P1129: Check that the oxygen sensors are connected correctly. Inspect the wiring for damage. Check the operation of oxygen sensors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1129?

Yes, but get it checked soon

How much does it cost to fix P1129?

The estimated repair cost for P1129 is $22–56. Actual cost depends on your vehicle, location, and labor rates.

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