P203B · Manufacturer communications

DODGE, FREIGHTLINER, MERCEDES-BENZ · 2026-03-23

The check engine light is illuminated, or the AdBlue warning is active, with recorded faults related to AdBlue quality or concentration. Complaint Customer reports an illuminated check engine light and or an AdBlue system warning indicating AdBlue quality out of specification. The vehicle may enter reduced performance mode. One or more of the following fault codes related to the AdBlue tank may be stored: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Background AdBlue must meet ISO 22241 quality requirements. ISO 22241 urea content limits for AdBlue are 31.8 percent to 33.2 percent by mass. AdBlue begins to crystallize and…

FREIGHTLINER, MERCEDES-BENZ · 2026-03-23

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 present in AdBlue (SCR) control unit (N118/5) Complaint The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes related to the AdBlue tank: P206B31 Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31 Malfunction of the AdBlue fill level sensor; the signal is absent. P300494 The quality of the AdBlue is insufficient. Cause A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The AdBlue concentration is outside ISO 22241 limits (below 31.8 percent or above 33.2 percent). C. Frozen or partially frozen AdBlue can cause the AdBlue level and concentration functions to report inaccurate values. D. The AdBlue…

FREIGHTLINER, MERCEDES-BENZ · 2026-03-23

Vehicles with SCR Generation 4: SCR/AdBlue® warning message cannot be reset with fault code P13DF00 or P300685 Complaint SCR or AdBlue warning message cannot be reset. All fault codes in the AdBlue (SCR) control unit have been processed and corrected, however fault codes P13DF00 or P300685 remain active and stored. Cause The procedure for resetting the SCR or AdBlue warning message with XENTRY Diagnosis has not been carried out. Note: If AdBlue quality or concentration related fault codes are present, such as P300494, P203B31, or P206B31, complete the applicable diagnostic procedure first. This includes the thaw, mixing drive, and retest requirements in LI49.20-N-080376 and the detailed diagnosis and re-pair steps in LI49.20-N-078838 as applicable. Do not attempt to reset the SCR or…

FREIGHTLINER, MERCEDES-BENZ · 2026-02-24

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 present in AdBlue (SCR) control unit (N118/5) Complaint The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes related to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to premature freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor to misread levels. D. The AdBlue…

FREIGHTLINER, MERCEDES-BENZ · 2025-03-18

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 when outside temperatures are below 32 degrees Fahrenheit. SCR Gen4 (KP7) Complaint: The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes rela- ted to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause: A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to prema- ture freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor…

DODGE, FREIGHTLINER, MERCEDES-BENZ · 2025-02-04

Complaint The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes rela- ted to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to prema- ture freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor to misread levels. D. The AdBlue level sensor is damaged. Remedy A. Software 1. Verify no newer software in AdBlue® SCR control unit (N118/5). 2. Complete…

FREIGHTLINER, MERCEDES-BENZ · 2025-02-04

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 when outside temperatures are below 32 degrees Fahrenheit

FORD · 2024-08-22

Some 2023-2024 F-Super Duty vehicles built on or before 22-Jul-2024 and equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P206B, and/or P2201:92 stored in the powertrain control module (PCM). This may be due to the software in the PCM. To correct the condition, follow the Service Procedure to reprogram the PCM using the latest software level of the Ford Diagnosis and Repair System (FDRS) scan tool.

FORD · 2024-08-22

Some 2024-2025 F-650/F-750 vehicles built on or before 22-Jul-2024 and equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P206B, and/or P2201:92 stored in the powertrain control module (PCM). This may be due to the software in the PCM. To correct the condition, follow the Service Procedure to reprogram the PCM using the latest software level of the Ford Diagnosis and Repair System (FDRS) scan tool.

FORD · 2024-02-27

Some 2023-2024 F-Super Duty vehicles equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) U02A2, P206B, P203B, P208A, P20FA, P20FD, and/or P20FC stored in the powertrain control module (PCM). Before performing normal diagnostics, inspect connectors C1273C (32 pin) and C406 (14 pin) for proper connection. Also disconnect and inspect C1415 (32 pin), C406 (14 pin), C4863 (7 pin) and C4864 (5 pin) on the 14405 vehicle harness for signs of terminal push out, water intrusion and/or corrosion. Refer to the Wiring Diagram for connector locations. Repair as necessary. Refer to Wiring Diagram Cell 005 for repair procedures.

FORD · 2023-08-28

Some 2023 F-Super Duty vehicles equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) U02A2, P206B, P203B, P208A, P20FA, P20FD, and/or P20FC stored in the powertrain control module (PCM). Before performing normal diagnostics, inspect connectors C1273C (32 pin) and C406 (14 pin) for proper connection. Also disconnect and inspect C1415 (32 pin), C406 (14 pin), C4863 (7 pin) and C4864 (5 pin) for signs of water intrusion and/or corrosion. Refer to the Wiring Diagram for connector locations. Repair as necessary. Refer to Wiring Diagram Cell 005 for repair procedures.

FORD · 2023-08-28

Some 2024 F-650/F-750 vehicles equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) U02A2, P206B, P203B, P208A, P20FA, P20FD, and/or P20FC stored in the powertrain control module (PCM). Before performing normal diagnostics, inspect connectors C1273C (32 pin) and C314 (14 pin) for proper connection. Also disconnect and inspect C1583 (32 pin), C314 (14 pin), C3616 (7 pin) and C3613 (5 pin) for signs of water intrusion and/or corrosion. Refer to the Wiring Diagram for connector locations. Repair as necessary. Refer to Wiring Diagram Cell 005 for repair procedures.

FORD · 2023-05-23

Some 2018-2021 F-150 vehicles equipped with a 3.0L diesel engine, 2016-2022 F-650/F-750 vehicles equipped with a 6.7L engine, and 2017-2022 F-Super Duty vehicles equipped with a 6.7L engine and built on or before 08-Mar-2022 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P21DD, P20BA. P20B9, P204C, P208A, P208B, P208C, P203B, P205B, P21CD and/or U02A2 in the powertrain control module (PCM). This may be due to water intrusion within connectors C3613 and/or C4851/C3610 on the reductant harness going to the reductant pump/heater assembly and the reductant level sensor/quality module. This may also be due to movement of the wiring harness causing terminal fretting. To correct the condition, follow the Service Procedure to replace the reductant…

MERCEDES-BENZ · 2022-07-01

Complaint Indicator lamp illuminates in instrument cluster, fault codes P203B31, P203B49 and P206B31 present in AdBlue® (SCR) control unit (N118/5). Cause Software for AdBlue® (SCR) control unit (N118/5) Remedy Update AdBlue Control Unit Software

FORD · 2022-05-17

Some 2018-2021 F-150 vehicles equipped with a 3.0L diesel engine, 2016-2022 F-650/F-750 vehicles equipped with a 6.7L engine, and 2017-2022 F-Super Duty vehicles equipped with a 6.7L engine and built on or before 08-Mar-2022 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P21DD, P20BA. P20B9, P204C, P208A, P208B, P208C, P203B, P205B, P21CD and/or U02A2 in the powertrain control module (PCM). This may be due to water intrusion within connectors C3613 and/or C4851/C3610 on the reductant harness going to the reductant pump/heater assembly and the reductant level sensor/quality module. This may also be due to movement of the wiring harness causing terminal fretting. To correct the condition, follow the Service Procedure to replace the reductant…

FORD · 2021-09-28

Some 2018-2020 F-150 vehicles built on or before 1-Apr-2020 equipped with a 3.0L diesel engine, 2017-2019 F-Super Duty vehicles built on or before 30-Oct-2019 equipped with a 6.7L engine and 2016-2019 F-650/F-750 vehicles built on or before 30-Oct-2019 equipped with a 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P21DD, P20BA. P20B9, P204C, P208A, P208B, P208C, P203B, P205B, P21CD and/or U02A2 in the powertrain control module (PCM). This may be due to water intrusion within connectors C3613 and/or C4851/C3610 on the reductant harness going to the reductant pump/heater assembly and the reductant level sensor/quality module. To correct the condition, follow the Service Procedure steps to replace the reductant tank harness, the…

FORD · 2021-09-14

This article supersedes TSB 21-2055 to update the Title, Issue, Action, vehicles affected and production fix date. Some 2020-2021 F-Super Duty vehicles equipped with a 6.7L engine built on or before 10-Feb-2021 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0300-P0308, P0603, P203B, P208B, P208C, P20EE, P2201, P24C2, P27B4, and/or P27B5 stored in the powertrain control module (PCM). The vehicle may also exhibit a forced idle condition. This may be due to various strategies within the PCM software. To correct the condition, follow the Service Procedure to reprogram the PCM.

FORD · 2021-08-31

This article supersedes TSB 17-0068 to update the Service Procedure and Parts List. Some 2016-2017 F-650/F-750 vehicles equipped with a 6.7L diesel engine and built on or before 21-Aug-2017 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble code (DTC) P203B. This may be due to a low voltage condition during engine cranking. To correct this condition, reflash the diesel exhaust fluid (DEF) reductant level sensor/quality module using the Urea Sensor Reprogramming tool.

FORD · 2021-03-04

This article supersedes TSB 20-2336 to update the Title, Issue, Action, vehicles affected and production fix date. Some 2020-2021 F-Super Duty vehicles equipped with a 6.7L engine built on or before 10-Feb-2021 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTCs) P0300-P0308, P054F, P0603, P203B, P208B, P208C, P20EE, P2201, P24C2, P27B4, and/or P27B5 stored in the powertrain control module (PCM). The vehicle may also exhibit a forced idle condition. This may be due to various strategies within the PCM software. To correct the condition, follow the Service Procedure to reprogram the PCM.

FORD · 2020-09-22

Some 2020 F-Super Duty vehicles equipped with a 6.7L engine built on or before 19-Aug-2020 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P0300-P0308, P0603, P203B, P208B, P208C, P2201, P24C2, P27B4, P07F6 and/or P27B5 stored in the powertrain control module (PCM). The vehicle may also exhibit a forced idle condition. This may be due to various strategies within the PCM software. To correct the condition, follow the Service Procedure to reprogram the PCM.

FORD · 2020-08-18

Some 2017 F-Super Duty vehicles equipped with a 6.7L diesel engine built on or before 04-Aug-2017 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble code (DTC) P203B. This may be due to a low voltage condition during engine cranking. To correct this condition, reflash the diesel exhaust fluid (DEF) reductant level sensor/quality module using the Urea Sensor Reprogramming tool.

MERCEDES-BENZ · 2020-07-08

Check engine light illuminates in instrument cluster, fault codes P203B31 or P203B49 or P206B31 present in AdBlue(R) (SCR) control unit

MERCEDES-BENZ · 2020-04-23

Check engine light on with fault codes P203B31, P203B49, P206B31, P13DF00 present in the SCR control unit

FORD · 2020-03-05

Some 2020 F-Super Duty vehicles equipped with a 6.7L engine built on or before 5-Feb-2020 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P2201 and/or DTC P27B4 stored in the powertrain control module (PCM). The vehicle may also exhibit a forced idle condition. This may be due to various strategies within the PCM software. To correct the condition, follow the Service Procedure to reprogram the PCM.

FORD · 2020-02-14

Some 2020 F-Super Duty vehicles equipped with a 6.7L engine built on or before 5-Feb-2020 may exhibit an illuminated malfunction indicator lamp (MIL) with diagnostic trouble codes (DTC) P203B, P2201 and/or DTC P274B stored in the powertrain control module (PCM). This may be due to various strategies within the PCM software. To correct the condition, follow the Service Procedure to reprogram the PCM.

FORD · 2020-01-27

Some 2020 F-Super Duty vehicles equipped with 6.7L engine may exhibit an illuminated malfunction indicator lamp (MIL) and diagnostic trouble code (DTC) P203B. If performing pinpoint test RJ in the Powertrain Control and Emission Diagnosis (PC/ED) does not identify an issue, do not attempt any repairs at this time. Engineering is currently investigating. Monitor OASIS for updates.

MERCEDES-BENZ · 2019-09-09

Engine diagnosis indicator lamp lights up in instrument cluster and fault code P203B00 is stored in the AdBlue® (SCR) control unit

MERCEDES-BENZ · 2019-03-25

Engine diagnosis indicator lamp lights up in instrument cluster and fault code P203B00 is stored in the AdBlue® (SCR) control unit

AUDI · 2019-03-15

This bulletin contains repair instructions for when a MIL is on with DTC P203B00.

LAND ROVER · 2018-10-10

A customer may raise a concern with the instrument pack displaying ?DEF Dosing Malfunction No Restarts in 250 Miles?. A Technician may find Diagnostic Trouble Code P203B-31 stored as a result.