P202D: Reductant Leakage

P202D reports that DEF is escaping somewhere between pump and dosing valve, which the controller typically notices as a pressure that cannot be held. Volvo and Mack use it on their 2014 and later trucks (OBD13 onwards). A 2015 tech tip handles it together with P208E and P20E8 and names poor electrical contact, which makes the pressure reading look low, and contamination that really lowers it. 2023 bulletins CBR-2298 and CBR-2303 add crystal crusts, a clogged tip or a weeping dosing valve, yet stress that returned valves were mostly fine: the valve is replaced only if a dosing test shows reduced flow. White urea crust on lines or the valve is a typical sign. CARB requires reductant delivery to be monitored. Neglected, the system cannot hold pressure, NOx rises and inducement follows.

Symptoms

• Malfunction indicator lamp on
• White crystalline deposits on DEF lines or dosing valve
• Higher DEF consumption, later inducement warnings

Most likely causes

• Dosing valve weeping or crusted with crystals
• Leaking DEF line, fitting or seal
• Poor electrical contact faking a pressure loss
• Contaminated DEF lowering system pressure

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the AdBlue/DEF level and quality, and do not add additives or water
2. Look for white crystals around the injector and the tank
3. Check connectors and heaters with the scanner
4. Run the dosing test available on your diagnostic tool
5. Replace parts only when the test points to that component

Good to know

• Repair difficulty: medium
• It can trigger limp mode.
• It affects emissions.

What each character of P202D means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 0: Subsystem depends on the code range
• 2D: Specific fault in that system

Frequently asked questions

Can I keep driving with code P202D?

Deal with it soon. If the instrument cluster shows a countdown, the car may not restart once it reaches zero.

What causes code P202D?

The most common causes are: dosing valve weeping or crusted with crystals; leaking DEF line, fitting or seal; poor electrical contact faking a pressure loss.

Related codes

• P208EReductant Injection Valve Stuck Closed (Bank 1 Unit 1)
• P20E8Reductant Pressure Too Low
• P204FReductant System Performance (Bank 1)

Sources

• static.nhtsa.gov: MC 10133613 9999
• static.nhtsa.gov: MC 10240252 0001
• static.nhtsa.gov: MC 10240202 0001
• law.cornell.edu: 13 CCR 1968.2

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.