AdBlue Temp. Sensor Kit PSA: P20E8 / U029E

The AdBlue system on PSA BlueHDi engines integrates an NTC thermistor in the urea tank to continuously measure the fluid temperature. This reading is essential: it controls the tank heating system and determines whether the ECU authorizes urea injection. When this sensor drifts or disconnects, the ECU reads an erroneous value, often 0°C at all times regardless of outside temperature, shuts down the pump, and sets fault codes P20E8 and/or U029E. The AdBlue warning light comes on, followed by the engine warning light, and the countdown appears on the dashboard: start lockout in X km.

Before any work, it is advisable to check the sensor with an ohmmeter to confirm the diagnosis. Disconnect the connector on the tank side and measure the resistance between the two yellow wires (20 kΩ range). A healthy sensor reads approximately 10,000 Ω at 20°C. A value below 1,000 Ω (shorted or drifting sensor) or infinite resistance (open circuit) confirms that the thermistor is faulty. In practice, a reading of around 280 to 300 Ω at room temperature is typical of a sensor that is permanently faulty.

This kit includes everything needed for a clean, durable repair:

• Stainless steel temperature sensor: NTC thermistor in stainless steel, resistant to urea corrosion. Resistance/temperature curve equivalent to the original part, recognized without fault by the ECU.
• Cable with urea-resistant sheathing: the protective sheath is formulated to withstand the chemical action of AdBlue over time.
• 2 waterproof connectors: for joining the 2 electrical wires, ensuring a sealed connection against urea splashes and moisture.
• 4 Rilsan cable ties: for a neat installation and secure cable retention in the engine bay.

The procedure requires removing the AdBlue tank from the vehicle, followed by opening only its removable section: the tank is neither replaced nor fully disassembled. Once access to the wiring is obtained, the original sensor is left in place: its wires are cut as close as possible, and the new sensor is connected directly to the harness using the supplied waterproof connectors. Clear the fault codes with a diagnostic scan tool to complete the job.

Primarily affected vehicles: 1.6 BlueHDi (DV6) and 2.0 BlueHDi (DW10) Euro 6.1 built up to November 30, 2019, as well as 1.5 (DV5), 2.0 (DW10) and 2.2 BlueHDi (DW12) Euro 6.2 built up to December 31, 2022.