Exhaust gas temperature (EGT) Bank 1
Last reviewed 2026-08-31
Mode 01 · PID 78 (decimal 120)
Description
Up to four EGT sensors on bank 1. Byte A is a support bitmap; each sensor is a 16-bit temperature with the catalyst-style scale.
- PID number
- 78 · 120
- Unit
- °C
- Range
- -40 … 6513.5
- Data bytes
- 9
- Formula
- Support in A; sensors ((hi*256)+lo)/10-40
Bit decode map
All engines
| Byte.bit | Field | Role |
|---|---|---|
| A0 | EGT sensor 1 supported | support |
| A1 | EGT sensor 2 supported | support |
| A2 | EGT sensor 3 supported | support |
| A3 | EGT sensor 4 supported | support |
- Also valid as Mode 02 freeze-frame data (same PID number, snapshot at last DTC).
Defined by SAE J1979 / ISO 15031-5. Public index — not a substitute for the paid SAE document.
Sources
Provenance for this page. Official standards outrank community notes. See the confidence policy.
Official standard · high trust
SAE J1979 / ISO 15031-5 Mode 01 PID formulas (public index)
J1979 public PID index: 01 78