OBD Guide
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P123E

Nitrogen Oxide Sensor Sensor Poisoning NOx Signal Too Low

P123E is an OBD-II diagnostic trouble code meaning: Nitrogen Oxide Sensor Sensor Poisoning NOx Signal Too Low. Common causes: use of low-quality fuel, sensor contamination with soot or oil. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Increased fuel consumption
  • Reduced engine power
  • Check Engine Light Illuminates
  • Increased level of harmful emissions
  • Unstable engine idling

Causes

  • Use of low-quality fuel
  • Sensor contamination with soot or oil
  • SCR system malfunction
  • Natural wear of the NOx sensor
  • Problems with the sensor wiring harness

How to Fix

  1. Check the NOx sensor for contamination
  2. Clean or replace NOx sensor if necessary
  3. Check the quality of the fuel used
  4. Diagnose the SCR system for malfunctions
  5. Check the integrity of the sensor wiring harness

Related codes

P123FP123DP123C

FAQ

What does the P123E code mean?

P123E is an OBD-II diagnostic trouble code that indicates: Nitrogen Oxide Sensor Sensor Poisoning NOx Signal Too Low

What causes a P123E error code?

The most common causes of P123E include: Use of low-quality fuel; Sensor contamination with soot or oil; SCR system malfunction; Natural wear of the NOx sensor.

How do I fix a P123E diagnostic trouble code?

To fix P123E: Check the NOx sensor for contamination. Clean or replace NOx sensor if necessary. Check the quality of the fuel used. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P123E?

Yes, but get it checked soon

How much does it cost to fix P123E?

The estimated repair cost for P123E is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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