OBD Guide

P126F

Nitrogen Oxide Sensor Trailing Throttle Check Linear Lambda Signal Too Rich

P126F is an OBD-II diagnostic trouble code meaning: Nitrogen Oxide Sensor Trailing Throttle Check Linear Lambda Signal Too Rich. Common causes: nox sensor malfunction, problems with the fuel injection system (re-rich mixture). 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 Is On
  • Increased emissions of harmful substances
  • Unstable engine idling

Causes

  • NOx sensor malfunction
  • Problems with the fuel injection system (re-rich mixture)
  • Dirty or faulty injectors
  • Problems with the EGR system
  • Oxygen sensor malfunction

How to Fix

  1. Check NOx sensor readings using diagnostic equipment
  2. Check the operation of the fuel injection system and the condition of the injectors
  3. Check the serviceability of the EGR system
  4. Check the operation of oxygen sensors
  5. If necessary, replace the NOx sensor

Related codes

FAQ

What does the P126F code mean?

P126F is an OBD-II diagnostic trouble code that indicates: Nitrogen Oxide Sensor Trailing Throttle Check Linear Lambda Signal Too Rich

What causes a P126F error code?

The most common causes of P126F include: NOx sensor malfunction; Problems with the fuel injection system (re-rich mixture); Dirty or faulty injectors; Problems with the EGR system.

How do I fix a P126F diagnostic trouble code?

To fix P126F: Check NOx sensor readings using diagnostic equipment. Check the operation of the fuel injection system and the condition of the injectors. Check the serviceability of the EGR system. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P126F?

Yes, but get it checked soon

How much does it cost to fix P126F?

The estimated repair cost for P126F is $56–167. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat