MODE 01 · PID 1F
Run time since engine start
This is an elapsed-time counter in seconds since engine start, not total engine hours or time since codes were cleared.
- Formula
256 × A + B- Data bytes
- 2
- Units
- s
A worked decoding example
Request: 01 1F
Response: 41 1F 01 2C
Data: 01 2C → 300 s
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
Use it to describe warm-up and sample context. A reset or a missing response should not be silently treated as zero seconds.
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
Formula256 × A + B → s
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
- python-OBD: Mode 01 command table ↗
- python-OBD: byte decoding implementation ↗
- CSS Electronics: OBD-II PID and response frames ↗
- California BAR: OBD test reference ↗
Independent reference; no affiliation with SAE, vehicle manufacturers or regulators. Sources checked 28 October 2026.