2019 BMW 128i Convertible (E88) L6-3.0L (N51) A L L Diagnostic Trouble Codes ( DTC ): Manufacturer Code Charts Page 116
Fault effect and breakdown warning
Driver information
Warning light:
MIL ON
Service instruction
none
2CA9
2CA9 - P0161
Information saved in
DME
Fault code
2CA9 - P0161
Fault text
Oxygen sensor heating behind catalytic converter 2, function
Fault description
O2 Sensor Heater Circuit (Bank 2 Sensor 2)
Condition for fault identification
Test condition:
Check internal resistance of O2 sensor to check sensor
heater => If the heater is too weak, the O2 sensor's internal
resistance rises too high (= sensor too cold)
No fault memories;
Terminal condition: Terminal 15, engine on
Voltage condition:
none
Condition for fault memory entry
Internal resistance R > 12000 Ohm (US) or 15000 Ohm
(ECE)
Action in service
0. Was the temperature drop caused by external factors
(driving into snow pile, ice on O2 sensor?) Thaw sensor,
clear all fault memory, continue driving!
1. Check O2 sensor heater: Contact resistance on plugs and
in wiring is excessive (DME - wiring harness - sensor)
2. Check wiring
3. Check O2 sensor plug (water or corrosion in the plug?
Repeatedly disconnect the plug and then re-insert it
FIRMLY)
4. Replace plug and/or wire as indicated
5. Replace the affected downstream (post-cat) O2 sensor
Fault effect and breakdown warning
