P0138

P0138 00

O2S Circuit. High Voltage. Sensor 2.







Fault symptom
Check Engine

On-board diagnosis

Type of diagnosis:
Continuous

Enable criteria:
Battery voltage must be between 11 - 16 V.
Engine running.
Preheating active for more than 4 s.
Secondary air pump not active, if fitted.
EVAP, leak diagnosis inactive (if OBD II).

Fault criteria:
When voltage across the sensor is more than 1200 mV for 5 s.

Dependent:
None

System reaction to a fault:
Preheating is switched off.
Adaption of rear oxygen sensor is blocked and reset.

OK report:
Fault criteria NOT fulfilled for 6 s.

Fault handling:
Type III
(See Description of On-Board Diagnostics/Fault handling III, "Other emission-related components and functions" for more information.)

Checking the wiring harness
Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.

Diagnostic help

Diagnosis regards:
Electrical fault in the connecting leads or component.

IMPORTANT: If the control module part no. is 55354002 for B202E/L or 55354562 for B207R, the control module shall be upgraded with the latest software because these part nos. can incorrectly detect the DTC. If the part. no. is later then the numbers listed here, carry out with normal fault tracing. The DTC can remain even after SPS programming because it is a valid fault.

Functions in the diagnostic tool related to the fault:
Test value:
- O2S 2