Fault Code 20B811 (The Output For The Heating Element Of The ADBLUE Delivery Module Has A Short Circuit To Positive) Is Stored In The ADBLUE Control Unit (LI49.20-P-053152)

Publication date: 2012-08-08
Reference number: LI49.20-P-053152

FAULT CODE 20B811 (THE OUTPUT FOR THE HEATING ELEMENT OF THE ADBLUE DELIVERY MODULE HAS A SHORT CIRCUIT TO POSITIVE) IS STORED IN THE ADBLUE CONTROL UNIT

TECHNICAL SERVICE BULLETIN

Reference Number(s): LI49.20-P-053152 Version 2, Date of Issue: August 08, 2012

Mercedes-Benz:	Model 463 with engine 642 and SA code MC7 (engine OM 642 D 30 BlueTEC); Model 164 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment); Model 251 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment); Model 212 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment); Model 166 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment); Model 166 with engine 651 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment); Model 221 with engine 642 and SA code U42 (BlueTEC (SCR) diesel exhaust treatment)
Design Group:	49.20 Exhaust aftertreatment unit
Reason For Change:	Remedy described in detail

COMPLAINT

Engine diagnosis warning lamp lights up.

Fault code 20B811 (The output for the heating element of the AdBlue delivery module has a short circuit to positive) is stored in the AdBlue control unit.

CAUSE

Due to excessively sensitive diagnostic routines, a fault entry for the heating element of the AdBlue delivery module may be logged during the warm-up phase at low outside temperatures.

REMEDY

Program BlueTec control unit (SCR) with new software

NOTE: The software is available with the following add-ons:

DVD 01/2012 - add-on 2274
DVD 03/2012 - add-on 2275
DVD 05/2012 - add-on 2306

If the fault code is still current even after programming the BlueTec control unit, process the test steps in XENTRY/Star Diagnosis for this fault code.

SYMPTOMS

Power generation / Engine management / Engine management indicator lamp / Engine diagnosis / lit

CONTROL UNIT/FAULT CODE

Control unit	Fault code	Fault text
SCR-Selective Catalytic Reduction (M (164), R (251), GL (164), S (221), G (463))	20B811	The output for the heating element of the AdBlue delivery module has a short circuit to positive.
SCR - Selective catalytic reduction (N118/5) (SCRCM) (E (212), M (166))	20B811	The output for the heating element of the AdBlue® delivery module has a short circuit to positive.