AutoCodes – Generic – P20C9

P20C9 Code - Diesel Exhaust Fluid Control Module Requested MIL Illumination

Quick Answer

The Diagnostic Trouble Code (DTC) will be set when the Diesel Exhaust Fluid (DEF) Control Module detects a problem with the DEF and requests the illumination of the Malfunction Indicator Light (MIL) to turn ON. Common causes include Check Diesel Exhaust Fluid (DEF) level and condition, Faulty Nitrogen Oxide (NOX) Sensor(s), Faulty Diesel Exhaust Fluid Control Module. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P20C9 indicates Diesel Exhaust Fluid Control Module Requested MIL Illumination.
Common causes: Common causes include Check Diesel Exhaust Fluid (DEF) level and condition, Faulty Nitrogen Oxide (NOX) Sensor(s), Faulty Diesel Exhaust Fluid Control Module.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 48,412

How popular is this code, among other codes? Medium

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Nov 08, 2023

Description
Possible Causes
How To Fix
Tech Notes ▶
Cost to Diagnose
FAQs
Comments
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Code P20C9 Description

OBDII Code P20C9 - Diesel Exhaust Fluid Control Module Requested MIL Illumination - AutoCodes.com — P20C9 Code - Diesel Exhaust Fluid Control Module Requested MIL Illumination

What does this mean?

What are the Possible Causes of the DTC P20C9?

Check Diesel Exhaust Fluid (DEF) level and condition
Faulty Nitrogen Oxide (NOX) Sensor(s)
Faulty Diesel Exhaust Fluid Control Module
Diesel Exhaust Fluid Control Module harness is open or shorted
Diesel Exhaust Fluid Control Module circuit poor electrical connection

How to Fix the DTC P20C9?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

User Submitted Video

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P20C9 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Information for Specific Makes

P20C9 Isuzu — Diesel Exhaust Fluid Control Module Requested MIL Illumination

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P20C9 Code

1. What are common symptoms of OBDII code P20C9?

The common symptoms of OBDII code P20C9 include the Check Engine Light (MIL) illuminating on the dashboard and potential issues with the Diesel Exhaust Fluid (DEF) system.

2. What does the OBDII code P20C9 indicate?

OBDII code P20C9 indicates a fault related to the Diesel Exhaust Fluid Control Module requesting MIL (Malfunction Indicator Lamp) illumination.

3. What are possible causes of OBDII code P20C9?

Possible causes of OBDII code P20C9 include a malfunctioning Diesel Exhaust Fluid Control Module, wiring or connection issues, low DEF fluid level, or a faulty DEF quality sensor.

4. How can I diagnose OBDII code P20C9?

Diagnosing OBDII code P20C9 typically involves using an OBDII scanner to retrieve the code, checking the DEF system components for any visible damage, inspecting wiring and connections, and testing the DEF quality sensor.

5. Can OBDII code P20C9 be fixed at home?

Depending on the root cause, some DIY enthusiasts may be able to fix OBDII code P20C9 at home by addressing issues such as topping up DEF fluid, checking and cleaning connections, or replacing a faulty DEF quality sensor.

6. Is it safe to continue driving with OBDII code P20C9 illuminated?

It is generally not recommended to continue driving with the OBDII code P20C9 illuminated, as it indicates a potential issue with the DEF system that could lead to reduced engine performance or emissions compliance.

7. How much does it typically cost to repair OBDII code P20C9 at a professional repair shop?

The cost of repairing OBDII code P20C9 at a professional repair shop can vary depending on the exact cause of the issue, but it may range from a couple of hundred to a few hundred dollars, including parts and labor.

8. Can resetting the OBDII code P20C9 turn off the Check Engine Light?

Resetting the OBDII code P20C9 may temporarily turn off the Check Engine Light, but if the underlying issue is not addressed, the light is likely to come back on once the fault is detected again by the vehicle's onboard diagnostics system.

9. What are the long-term effects of ignoring OBDII code P20C9?

Ignoring OBDII code P20C9 can lead to potential issues with the DEF system, reduced fuel efficiency, and increased emissions output. It is advisable to address the problem promptly to prevent further complications.

10. How often does OBDII code P20C9 occur in diesel vehicles?

OBDII code P20C9 related to the Diesel Exhaust Fluid Control Module is more common in modern diesel vehicles equipped with DEF systems to meet emission standards, especially if maintenance or quality sensor issues arise.