What causes B0408 on a Chevy?

Binding or stripped gears in the driver side front temperature door actuator Open or short in the driver side actuator control circuit Corroded or loose driver side actuator connector Failed door position sensor inside the driver side actuator Faulty driver side output in the HVAC control module

How do I fix B0408 on a Chevy?

Confirm the code with a scan tool Inspect and reseat the driver side actuator connector Test the driver side actuator control circuit for opens, shorts and voltage drop Command the driver side door with the scan tool and watch its travel Repair damaged wiring before replacing any parts Replace the actuator or HVAC control module only after circuit tests pass, then clear the code and retest

Code

B0408

Front temperature control circuit malfunction

Q: What does B0408 mean on a Chevy?

B0408. Front temperature control circuit malfunction. The HVAC module cannot hold the driver side temperature and the body warning light comes on. Applies to Chevrolet, GMC, Buick, Cadillac, Pontiac, Oldsmobile and Saturn models that use this code.

Category: Body
Severity: Body Warning Light
Applies to: Chevrolet, GMC, Buick, Cadillac, Pontiac, Oldsmobile and Saturn models that use this code
Related: No single generic twin. See OBD Codes List

What it means

B0408. Front temperature control circuit malfunction. The HVAC module cannot hold the driver side temperature 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

Binding or stripped gears in the driver side front temperature door actuator
Open or short in the driver side actuator control circuit
Corroded or loose driver side actuator connector
Failed door position sensor inside the driver side actuator
Faulty driver side output in the HVAC control module

Standard procedure

Confirm the code with a scan tool
Inspect and reseat the driver side actuator connector
Test the driver side actuator control circuit for opens, shorts and voltage drop
Command the driver side door with the scan tool and watch its travel
Repair damaged wiring before replacing any parts
Replace the actuator or HVAC control module 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: checked against the recorded source material.

Code B0408 definition | OBDII.pro
live manufacturer definition (obdii.pro)
Supports: GM manufacturer meaning for B0408
Fetched directly. The GM entry is the brand-family meaning used here. This site is independent of engine-codes and autocodes.
B0408 CHEVROLET Front Temperature Control Circuit | Engine-Codes.com
archived reference page (engine-codes.com via Wayback Machine)
Supports: Chevrolet meaning and possible causes for B0408
Fetched directly. Model and year fitment remain curator claims.
B0408 CHEVROLET Front Temperature Control Circuit | AutoCodes.com
archived reference page (autocodes.com via Wayback Machine)
Supports: corroboration of Chevrolet meaning and causes for B0408
Same Chevrolet text as the engine-codes page (both sites share one publisher).

Last updated 2026-10-10.

Report a correction for B0408. Include your vehicle, the issue and a source if you have one.