OBD Guide

P20C9

Reductant Control Module Requested MIL Illumination

P20C9 is an OBD-II diagnostic trouble code meaning: Reductant Control Module Requested MIL Illumination. Common causes: reducer control module malfunction, low level or poor quality of reagent (adblue). Estimated repair cost: $17–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$17–89 (est.)

Symptoms

  • Check Engine light is on
  • Reduced engine power (emergency operation mode)
  • Increased fuel consumption
  • Unpleasant exhaust smell
  • Error message on display

Causes

  • Reducer control module malfunction
  • Low level or poor quality of reagent (AdBlue)
  • Problems with NOx sensors
  • Open or short circuit in control circuit
  • Software error in SCR module

How to Fix

  1. Check the level and quality of AdBlue reagent
  2. Diagnose the reductant control module
  3. Check NOx sensors and their wiring
  4. Scan the system for other related codes
  5. Update SCR module software if necessary

Related codes

Error P20C9 by Vehicle Brand

FAQ

What does the P20C9 code mean?

P20C9 is an OBD-II diagnostic trouble code that indicates: Reductant Control Module Requested MIL Illumination

What causes a P20C9 error code?

The most common causes of P20C9 include: Reducer control module malfunction; Low level or poor quality of reagent (AdBlue); Problems with NOx sensors; Open or short circuit in control circuit.

How do I fix a P20C9 diagnostic trouble code?

To fix P20C9: Check the level and quality of AdBlue reagent. Diagnose the reductant control module. Check NOx sensors and their wiring. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P20C9?

Limited driving only, diagnose soon

How much does it cost to fix P20C9?

The estimated repair cost for P20C9 is $17–89. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat