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Short Circuit Faults Concerning Oxygen Sensor Stored In CDI Control Unit (LI49.20-P-053609)

Publication date: 2016-03-01
Reference number: LI49.20-P-053609

SHORT CIRCUIT FAULTS CONCERNING OXYGEN SENSOR STORED IN CDI CONTROL UNIT

SHORT CIRCUIT FAULTS CONCERNING OXYGEN SENSOR STORED IN CDI CONTROL UNIT

TECHNICAL SERVICE BULLETIN

Reference Number(s): LI49.20-P-053609 Version 4, Date of Issue:  March 1, 2016
Mercedes-Benz: Model 164 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment)
Design Group: 49.20 Exhaust aftertreatment unit
Reason For Change: updated remedy

COMPLAINT

Engine diagnosis warning lamp lights up

The following faults may be stored in the CDI control unit:

  1. Fault code 14E300

    The output for the heater of oxygen sensor 1 (cylinder bank 1) has an electrical fault or an open circuit

  2. Fault code 14E700

    Oxygen sensor 1 (cylinder bank 1) has a short circuit to positive

  3. Fault code 14E800

    Oxygen sensor 1 (cylinder bank 1) has a short circuit to ground

CAUSE

There may be transition resistances in the electrical lines or connectors between N3/9 (CDI control unit) and the component G3/2 (O2 sensor).

REMEDY

Process codes through SDS. If the guided tests do not provide resolution follow steps outlined below.

  1. Check the O2 sensor connector (G3/2x1 at the right rear top of the engine) between N3/9 (CDI control unit) and the component G3/2 (O2 sensor) for correct engagement.

    If the connector is correctly engaged, continue with step 2.

  2. Check connector G3/2x1 (O2 sensor connector) for widened female contacts. If the female contacts are widened, replace connector and female contacts.
  3. Check wiring on engine harness side for any chafing / damage. If damage is found, repair as required.

    For MY 2010 vehicles only (SA 800) - if no damage is found, continue with step 4.

  4. Cut wiring to the G3/2x1 (O2 sensor connector) on the engine harness approx. 1 inch before the connector.
  5. Repair engine wiring harness (connector A046 545 91 28) and replace O2 sensor.

CONTROL UNIT/FAULT CODE

CONTROL UNIT/FAULT CODE

Control unit Fault code Fault text
CDI 6BIN5-Common Rail Diesel Injection (CDI6BIN5) 14E300 The output for the heater of oxygen sensor 1 (cylinder bank 1) has an electrical fault or open circuit.
CDI 6BIN5-Common Rail Diesel Injection (CDI6BIN5) 14E700 Oxygen sensor 1 (cylinder bank 1) has a short circuit to positive.
CDI 6BIN5-Common Rail Diesel Injection (CDI6BIN5) 14E800 Oxygen sensor 1 (cylinder bank 1) has a short circuit to ground.

PARTS

PARTS

Part number ES1 ES2 Designation Quantity Note EPC
A 000 545 36 43     Connector 6-pin MLK with coding B 1   X
A 003 982 70 26     Female contact MLK 1.2 Sm silver-plated for 0.5 mm2 3   X
A 003 982 73 26     Female contact MLK 1.2 Sm silver-plated for 0.75 mm2 2   X
A 046 545 91 28     Connector 6-pin 1 If needed X
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