MODE 01 · PID 05

Engine coolant temperature

This is the ECU coolant sensor reading. It is not an infrared measurement of the radiator, and its encoding range is not a safe operating range.

Formula
A − 40
Data bytes
1
Units
°C

A worked decoding example

Request: 01 05

Response: 41 05 7B

Data: 7B → 83 °C

The example shows service, PID and data only. It omits adapter headers, CAN identifier, length and padding. It is not a live vehicle reading.

Reading context

For a cold-soak comparison, record ambient and intake-air readings before starting. During warm-up, compare the trend with the vehicle service procedure.

A decoded value is a measurement, not a diagnosis. Encoding limits are not normal operating limits. Confirm vehicle support and the manufacturer’s procedure.

Byte decoder

Your input stays in this browser.MODE 01

FormulaA − 40 → °C

A decoded value is a measurement, not a diagnosis. Encoding limits are not normal operating limits. Confirm vehicle support and the manufacturer’s procedure.

Sources

  1. python-OBD: Mode 01 command table ↗
  2. python-OBD: byte decoding implementation ↗
  3. CSS Electronics: OBD-II PID and response frames ↗
  4. California BAR: OBD test reference ↗

Independent reference; no affiliation with SAE, vehicle manufacturers or regulators. Sources checked 28 October 2026.