OBD Guide
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P125C

Nitrogen Oxide Sensor Heating Supply Voltage

P125C is an OBD-II diagnostic trouble code meaning: Nitrogen Oxide Sensor Heating Supply Voltage. Common causes: open or short circuit in nox sensor heating circuit, malfunction of the nox sensor itself. Estimated repair cost: $50–167.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$50–167 (est.)

Symptoms

  • Check Engine Light Is On
  • Reduced engine power
  • Increased fuel consumption
  • Problems starting the engine in cold weather

Causes

  • Open or short circuit in NOx sensor heating circuit
  • Malfunction of the NOx sensor itself
  • Heater fuse or relay problems
  • Engine ECU malfunction
  • Poor contact in sensor connectors

How to Fix

  1. Check the integrity of the wiring to the NOx sensor
  2. Check the fuse and relay of the heating circuit
  3. Measure the resistance of the sensor heating element
  4. Check sensor connectors for corrosion or damage.
  5. If necessary, replace the NOx sensor

Related codes

P125DP125EP125F

FAQ

What does the P125C code mean?

P125C is an OBD-II diagnostic trouble code that indicates: Nitrogen Oxide Sensor Heating Supply Voltage

What causes a P125C error code?

The most common causes of P125C include: Open or short circuit in NOx sensor heating circuit; Malfunction of the NOx sensor itself; Heater fuse or relay problems; Engine ECU malfunction.

How do I fix a P125C diagnostic trouble code?

To fix P125C: Check the integrity of the wiring to the NOx sensor. Check the fuse and relay of the heating circuit. Measure the resistance of the sensor heating element. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P125C?

Yes, but get it checked soon

How much does it cost to fix P125C?

The estimated repair cost for P125C is $50–167. Actual cost depends on your vehicle, location, and labor rates.

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