18-034-21 REV. A

NUMBER:
GROUP:
DATE:
18-034-21 REV. A
18 - Vehicle Performance
November 10, 2021
This bulletin is supplied as technical information only and is not an authorization for repair. No part of this publication may be reproduced, stored in a retrieval system, or
transmitted, in any form or by any means, electronic, mechanical, photocopying, or otherwise, without written permission of FCA US LLC.
This bulletin supersedes Technical Service Bulletin (TSB) 18-034-21, date of issue April 02,
2021, which should be removed from your files. All revisions are highlighted with
**asterisks** and include 2022 model year.
SUBJECT:
P203E and P203F Additional Diagnostic Information
OVERVIEW:
This bulletin provides additional information regarding diagnosing Diesel Exhaust Fluid (DEF) issue
in extreme cold weather. Diagnostic Trouble Codes (DTCs) P203E - Reductant Level Sensor 1
Circuit Intermittent and/or P203F - Reductant Level Too Low set.
MODELS:
2019 - **2022**
(DJ)
RAM 2500 Pickup
2019 - **2022**
(D2)
RAM 3500 Pickup
2019 - **2022**
(DD)
RAM 3500 Cab Chassis
2019 - **2022**
(DP)
RAM 4500/5500 Cab Chassis
NOTE: This bulletin applies to vehicles within the following markets/countries: North
America, LATAM, EMEA and APAC.
NOTE: This bulletin applies to vehicles equipped with a 6.7L I6 Cummins Turbo Diesel
Engine (Sales Codes ETL or ETN) or 6.7L I6 Cummins HO Turbo Diesel Engine (Sales
Code ETM).
DISCUSSION:
Several reports have been received of vehicles in the field setting DTCs P203E and/or P203F.
Many of these vehicles were located in areas of extreme cold, or in areas where the temperatures
can go from extreme cold to warm in short periods of time. An analysis of returned parts from
several of these vehicles has shown a high rate of No Trouble Found (NTF). Further analysis of
information returned from the field, has narrowed down the cause into three possible scenarios.
• Scenario #1 - DEF Tank Overfilled.
• Scenario #2 - Residual Ice in the DEF Tank or Covering the Level Sensor.
• Scenario #3 - DEF Crystallization Covering the Level Sensor.
NOTE: If you encounter a vehicle with any of the above conditions, please review each
scenario below and repair accordingly prior to replacing any parts.
DEF Level Sensor Operation:
The DEF level sensor is new starting in the 2019 Model Year. The new design level sensor uses an
Ultrasonic Frequency (UF) signal to detect the proper fluid level. Previous model years use a radio
frequency type sensor which operates differently, and can be less accurate.
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In order for the UF level sensor to operate properly, it is crucial that there is sufficient air space
between the top level of the fluid, and the top of the DEF tank. DEF tanks are specially designed to
have an air space above the fluid, which is crucial for the level sensor to function. Without that air
space, the UF signal cannot be returned to the sensor properly leading to a “No Echo” condition.
Scenario #1: DEF Tank Overfill
One leading cause of P203E is due to the DEF tank being overfilled. If the DEF tank is overfilled,
the fluid will take up the air space designed into the top of the tank, leading to the “no echo”
condition with the sensor. This will cause P203E to set.
Scenario #1 Repair:
To correct the overfill condition, the DEF tank will need to be drained to the proper level. Once
drained, verify the “DEF Level (Hardwired)” now reads a valid level (not 0%).
Does the DEF Level (Hardwired) reading now read a valid level?
• YES>>> Follow the P203E Drive Cycle below.
• NO>>> Refer to Scenario #3.
Scenario #2: Residual Ice
Another cause of P203E and P203F is residual ice in the DEF tank. Once ambient temperatures
reach approximately 12°F (-11°C), the DEF fluid in the tank will freeze. The P203E diagnostic
will not run if the DEF tank, and ambient temperatures stay below 39°F (4°C). However, as the
ambient temperature warms up, and the tank begins to thaw, the DEF tank may not be completely
thawed by the time the P203E DTC enabling criteria are met. If there is a residual layer of ice in the
tank, the ice will cause the “no echo” condition setting P203E. Vehicles are especially susceptible
to having residual ice in the tank, in areas where there is a large swing in temperatures (from
extreme cold to warm), in a short period of time. Additionally, if ice is covering the sensor
(Fig. 1) when the temperatures are too cold to run the P203E monitor, it could lead to P203F. Even
if there is sufficient fluid level in the tank.
Fig. 1
DEF Pump Assembly
1 - Ice In Level Sensor Focus Tube
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18-034-21 REV. A
Scenario #2 Repair:
To correct this scenario, the DEF tank must be fully thawed out. Allow the vehicle to sit in a heated
shop or garage overnight to thaw. If necessary, remove the DEF pump to drain the fluid, and
remove all residual ice. Take care when removing the DEF pump to avoid damage to the pump, and
heater mat. Once all the ice has been removed or thawed, follow the P203E Drive Cycle below.
Scenario #3: DEF Crystallization Covering the Level Sensor
Another cause of P203E and P203F is the DEF level sensor being covered in a layer or DEF
crystals, or ice (Fig. 2) . Vehicles that are in extreme cold for long periods of time can start to have
a buildup of DEF crystals on the bottom of the tank. When DEF tanks are completely frozen for long
periods of time, evaporation will start to occur. This evaporation of the ice will leave DEF
crystallization.
Fig. 2
DEF Crystallization Buildup In Level Sensor Focus Tube
NOTE: Do NOT clean DEF system components using regular tap water. The mineral content
in tap water can cause issues with the system. Only use fresh DEF fluid, or warm,
distilled water to clean crystallization from the DEF components.
CAUTION! Take care not to allow DEF fluid to come in contact with any electrical
connections or wiring. This will cause rapid corrosion to form.
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Scenario #3 Repair:
Unless the DEF fluid shows signs of contamination, crystallization that has formed in the tank, and
on the pump components can be cleaned without having to replace any parts. Flush the tank,
and clean the pump components using fresh DEF, or warm distilled water. In some instances, it may
be necessary to remove the DEF tank, and agitate the fluid by shaking the tank. Thoroughly drain
the DEF or distilled water used to clean the crystallization, and add fresh DEF. If P203E was set,
follow the P203E Drive Cycle below.
P203E Drive Cycle:
NOTE: When performing the drive cycle to clear the message, please drive as steadily as
possible at highway speeds. Avoid excessive stop and go, large bumps, or excessive
curves in the road to keep fluid slosh in the DEF tank at a minimum. Excessive fluid
slosh in the tank will delay the monitor from passing leading to inability to clear
the message.
CAUTION! If the vehicle is in a derated power state, safely drive the vehicle at the derated
speeds for a minimum of 15 minutes as steadily as possible to avoid tank slosh.
To clear the “Service DEF” message set by P203E, and ensure the vehicle is repaired, please drive
the vehicle under the following operating conditions.
• Steady state driving at highway speeds for a minimum of 15 minutes with minimal stopping and
starting to reduce DEF Tank sloshing.
• Ambient temperature greater than 4°C (39°F).
• DEF tank temperature (as reported by the temperature sensor) greater than 4°C (39°F).
• DEF tank temperature (as reported by the Urea Quality Sensor) 4°C (39°F).
NOTE: If the DTC goes stored, and the “Service DEF” message on the EVIC no longer
appears, top off the DEF tank to the proper level, and release it back to the customer.
DO NOT replace the DEF pump unit if this DTC was caused by overfilling of the tank
or crystalline buildup on the sensor.
POLICY:
Information Only