In-use performance tracking (spark ignition)
Last reviewed 2026-08-31
Mode 09 · PID 08 (decimal 8)
Description
In-use Monitor Performance Ratio (IUMPR) for spark engines: paired numerator/denominator counters (OBDCOND, IGNCNTR, CATCOMP1, CATCOND1, O2SCOMP1, …). See decode table on this PID page.
- PID number
- 08 · 8
- Unit
- —
- Range
- —
- Data bytes
- 4
- Formula
- Numerator/denominator pairs (CAT, O2, EGR, EVAP, AIR, …)
Field sequence
Ordered sub-fields inside the PID payload (each pair is typically two bytes).
| # | Mnemonic | Meaning |
|---|---|---|
| 1 | OBDCOND | OBD monitoring conditions encountered Denominator: how often OBD monitoring conditions were met. |
| 2 | IGNCNTR | Ignition counter Engine-start / ignition counter for IUMPR context. |
| 3 | CATCOMP1 | Catalyst monitor completions — bank 1 Numerator: catalyst monitor completed on bank 1. |
| 4 | CATCOND1 | Catalyst monitor conditions — bank 1 Denominator: conditions met for bank 1 catalyst monitor. |
| 5 | CATCOMP2 | Catalyst monitor completions — bank 2 Numerator: catalyst monitor completed on bank 2. |
| 6 | CATCOND2 | Catalyst monitor conditions — bank 2 Denominator: conditions met for bank 2 catalyst monitor. |
| 7 | O2SCOMP1 | O2 sensor monitor completions — bank 1 Numerator: O2 monitor completed on bank 1. |
| 8 | O2SCOND1 | O2 sensor monitor conditions — bank 1 Denominator: conditions met for bank 1 O2 monitor. |
| 9 | O2SCOMP2 | O2 sensor monitor completions — bank 2 Numerator: O2 monitor completed on bank 2. |
| 10 | O2SCOND2 | O2 sensor monitor conditions — bank 2 Denominator: conditions met for bank 2 O2 monitor. |
| 11 | EGRCOMP | EGR monitor completions Numerator: EGR monitor completed. |
| 12 | EGRCOND | EGR monitor conditions Denominator: conditions met for EGR monitor. |
| 13 | AIRCOMP | Secondary air monitor completions Numerator: AIR monitor completed. |
| 14 | AIRCOND | Secondary air monitor conditions Denominator: conditions met for AIR monitor. |
| 15 | EVAPCOMP | EVAP monitor completions Numerator: evaporative leak monitor completed. |
| 16 | EVAPCOND | EVAP monitor conditions Denominator: conditions met for EVAP monitor. |
| 17 | SO2SCOMP1 | Secondary O2 monitor completions — bank 1 Numerator: secondary O2 monitor completed on bank 1. |
| 18 | SO2SCOND1 | Secondary O2 monitor conditions — bank 1 Denominator: conditions met for secondary O2 monitor on bank 1. |
| 19 | SO2SCOMP2 | Secondary O2 monitor completions — bank 2 Numerator: secondary O2 monitor completed on bank 2. |
| 20 | SO2SCOND2 | Secondary O2 monitor conditions — bank 2 Denominator: conditions met for secondary O2 monitor on bank 2. |
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: 09 08