P248D code meaning
Reductant Heater B Sense Circuit High
Powertrain system Generic code P24xx codes Check engine light
What P248D means
P248D means the heater B sense input reads too high, typically the heated line. Possible pictures are a sense wire shorted to battery positive, a supply that remains on after the heater has been switched off, or a faulty input stage. Public maker documentation for P248D does not exist. GM tests the line heater sense circuit only for undervoltage (P248C); Ford's 2023 diesels cover heater circuit 2, the pressure line heater, with P20C0 (switched off yet more than 5 V at the output) and the current codes P221C/P221D. CARB requires the reductant heating to be monitored. A line heater that never switches off wastes battery energy and can overheat the hose, so the relay is the first item to check.
P248D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P248D
- Warning lamp
- Battery discharging while parked
Common causes of P248D
- PossibleLine heater relay sticking closed
- PossibleSense wire shorted to battery positive
- Less likelyDefective input stage in the module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Reductant heater b
What each part of P248D means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 8D | The exact fault in that area. |
What to do next
- Note P248D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P248D
What does P248D mean?
P248D means "Reductant Heater B Sense Circuit High". P248D means the heater B sense input reads too high, typically the heated line. It is a generic code, so it means the same on every make.
Is it safe to drive with P248D?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P248D fail an emissions test?
Yes, it can. P248D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P248D to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P248D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.