What are the common causes of P20ED?

A failing SCR NOx pre-catalyst on bank 1. A clogged or failing reductant injector. Low or contaminated reductant in the tank. A failing reductant pump. An exhaust leak or blockage ahead of the pre-catalyst.

Check the reductant level and top off the tank. Inspect and clean the reductant injector. Inspect the exhaust system for leaks or blockages. Read bank 1 NOx pre-catalyst temperature data with a scan tool. Replace the SCR NOx pre-catalyst if it keeps overheating. Clear the code and retest.

P20ED

SCR NOx Pre-Catalyst - Over Temperature Bank 1

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

What it means

P20ED means SCR NOx Pre-Catalyst - Over Temperature Bank 1.

Check these first

A failing SCR NOx pre-catalyst on bank 1
A clogged or failing reductant injector
Low or contaminated reductant in the tank
A failing reductant pump
An exhaust leak or blockage ahead of the pre-catalyst

What to do next

Check the reductant level and top off the tank
Inspect and clean the reductant injector
Inspect the exhaust system for leaks or blockages
Read bank 1 NOx pre-catalyst temperature data with a scan tool
Replace the SCR NOx pre-catalyst if it keeps overheating
Clear the code and retest

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Updated

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