OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Body generic / SAE

B0040

Outside Temperature Sensor Circuit

The HVAC or body control module has detected an implausible signal from the outside (ambient) temperature sensor. The displayed outside temperature may be wrong or missing and automatic climate control may behave incorrectly.

SystemBody
Typegeneric / SAE
GroupB0
Range / number– / 40

Possible causes

  • Ambient temperature sensor failed high
  • Wiring or connector fault to sensor medium

Symptoms

  • Warning light or symbol related to the affected system
  • Comfort or safety function impaired

Inspection / repair

  • Difficulty: easy
  • DIY: possible
  • Estimated cost: 30–150 €
  • Estimated time: 0.3–1 h
  • Component: outside temperature sensor
  • Component: hvac control module
  • Component: body control module

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication