B048D
Auxiliary heater temperature command circuit fault
What it means
B048D. Auxiliary heater temperature command circuit fault. The HVAC module cannot command the electric auxiliary heater and the body warning light comes on.. This Chevy-enhanced code applies to Chevrolet, GMC, Buick, Cadillac, Pontiac, Oldsmobile and Saturn models that use this code.
Findings, check these first
- Failed electric auxiliary heater
- Open or short in the auxiliary heater temperature command circuit
- Corroded auxiliary heater connector
- Failed command driver in the HVAC control module
- Blown auxiliary heater supply fuse
Standard procedure
- Confirm the code with a scan tool
- Check the auxiliary heater supply fuse
- Inspect and reseat the auxiliary heater connector
- Test the auxiliary heater command circuit for opens and shorts
- Command the auxiliary heater with the scan tool and watch for output
- Replace the electric auxiliary heater only after circuit tests pass, then clear the code and retest
Look up another code
Press / to jump to the box. Chevy-enhanced powertrain, body, chassis and network codes.
Sources and review
Review: qualified. Read the source limits below.
- B048D CHEVROLET Code: Meaning, Causes, and Symptoms | OBD2 Codes - OBD2 Codes
live reference page (obd2-codes.co)
Supports: CHEVROLET and GM-family meaning and likely causes for B048D
Fetched directly. B048D reads "Auxiliary Heater Temperature Command Circuit".
Last updated 2026-10-10.
Report a correction for B048D. Include your vehicle, the issue and a source if you have one.