What are the common causes of P248A?

A failed reductant heater A. An open in the heater A sense wire. Corrosion at the heater A sense connector. A low DEF level that stops the heater from drawing current.

Read reductant heater A status and DEF level on a scan tool. Check the heater A sense wire for an open circuit. Inspect the heater A sense connector for corrosion. Test heater A resistance against the service specification. Replace the reductant heater A if its resistance is out of spec. Clear the code and retest.

P248A

Reductant Heater A Sense Circuit Low

System: Auxiliary emission controls (P code)
Lamp: Check Engine Light
Category: Powertrain - Auxiliary Emissions Controls

What it means

P248A means Reductant Heater A Sense Circuit Low.

Check these first

A failed reductant heater A
An open in the heater A sense wire
Corrosion at the heater A sense connector
A low DEF level that stops the heater from drawing current

What to do next

Read reductant heater A status and DEF level on a scan tool
Check the heater A sense wire for an open circuit
Inspect the heater A sense connector for corrosion
Test heater A resistance against the service specification
Replace the reductant heater A if its resistance is out of spec
Clear the code and retest

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Updated

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