Powertrain, generic (extended)

P24D3 Reductant Heater B Sense Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modeNo

P24D3 is the same kind of fault for heater B, which GM and Ford assign to the heated DEF line from pump to dosing valve. The read-back line of this heater is broken or delivers nonsense, so the controller cannot tell whether the hose is really powered; the narrower low and high cases are P248C and P248D. No manufacturer documents P24D3 in this sense. FCA uses the number differently: bulletin 18-008-23 for 2019 Jeep Compass diesels outside North America lists P24D3-00 as a particulate matter sensor supply voltage above threshold, fixed with new PCM software. GM's diesel tables from 2016 to 2018 describe a line heater sense check with a 3 V limit. A line that does not thaw blocks dosing in winter, so the fault deserves attention before frost.

Likely causes

Open sense wire or loose plug at the heated DEF line

Damaged heated line with internal conductor fault

Manufacturer-specific use of the code (FCA uses it for PM sensor supply), software update

Symptoms

Malfunction indicator lamp on
DEF dosing faults or warnings at low temperatures

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–900

Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant heater b

Related codes

P24D2 P248C P248D P20BD

References: gsi.ext.gm.com, static.nhtsa.gov, law.cornell.edu.