P0139 on Toyota Passo (KGC10): Oxygen Sensor Slow Response (B1S2)

Short answer: P0139 means “Oxygen Sensor Slow Response (B1S2)”. The car’s computer has found a fault in the Engine - O2 system and turns on the Check engine light (MIL). First check: not given in source; see Toyota/Daihatsu repair manual DTC section.

Code

P0139

System

Engine - O2

Dashboard light

Check engine light (MIL)

Also sold as

Daihatsu Boon, Daihatsu Sirion (M300)

Applies to

Unverified for 1st-gen Passo/Boon; 1KR-FE (toyota-club.net list covers all 1KR-FE variants; 1st-gen KGC10/15 fitment not individually confirmed)

Confidence

low - NOT in Daihatsu M300 factory chart (B8-52..55); likely later-gen/Toyota-built 1KR only

Source

toyota-club.net

Symptoms and when it is set

1. Not given in source

Likely causes

1. Not given in source (code list only)

What to check, in order

1. Not given in source; see Toyota/Daihatsu repair manual DTC section

Related on this car

• All fault codes for this car
• Warning lights
• Where the parts are (parts map)
• Common problems

← P0138 P0140 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.