What are the common causes of P20D9?

A short to ground on the fuel supply control wire. An open in the fuel supply control power feed. Low aftertreatment fuel pressure. A failed aftertreatment fuel pressure sensor.

Read the exhaust aftertreatment fuel supply control circuit on a scan tool. Test the fuel supply control wire for a short to ground. Check the aftertreatment fuel pressure. Test the fuel pressure sensor signal. Replace the fuel pressure sensor if the supply pressure is correct. Clear the code and retest.

P20D9

Exhaust Aftertreatment Fuel Supply Control Circuit Low

System: Fuel and air metering (P code)
Lamp: Check Engine Light
Category: Powertrain - Fuel/Air Metering

What it means

P20D9 means Exhaust Aftertreatment Fuel Supply Control Circuit Low.

Check these first

A short to ground on the fuel supply control wire
An open in the fuel supply control power feed
Low aftertreatment fuel pressure
A failed aftertreatment fuel pressure sensor

What to do next

Read the exhaust aftertreatment fuel supply control circuit on a scan tool
Test the fuel supply control wire for a short to ground
Check the aftertreatment fuel pressure
Test the fuel pressure sensor signal
Replace the fuel pressure sensor if the supply pressure is correct
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.