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Mode 01 • PID 39

OBD2 PID 0139

O2S6_WR_lambda(1): Equivalence Ratio

Definition

Mode
01 (hex)
PID
39 (hex)
Data bytes
4
Formula
((A*256)+B)/32768
Range
0 – 2 N/A
Units
N/A

How to read PID 0139

Send mode 01 with PID 39 over OBD-II. The ECU returns 4 data byte(s), decoded with ((A*256)+B)/32768 (A, B, C, D are the returned bytes in order). The result is “O2S6_WR_lambda(1): Equivalence Ratio” in N/A. This is standard SAE J1979 data supported by most OBD-II scan tools and loggers.

Why it matters for tuning

Live PIDs like this are how tuners and workshops verify a remap on the road — logging RPM, load, boost, lambda and temperatures to confirm the map is safe. The desktop Softechpro Solutions software complements live logging with offline ECU editing: DPF/EGR/AdBlue/DTC off and Stage tuning with automatic checksum.

Related PIDs

0135 O2S2_WR_lambda(1): Equ0136 O2S3_WR_lambda(1): Equ0137 O2S4_WR_lambda(1): Equ0138 O2S5_WR_lambda(1): Equ013A O2S7_WR_lambda(1): Equ013B O2S8_WR_lambda(1): Equ013C Catalyst Temperature B013D Catalyst Temperature B

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