Loading...

Bmw 335D Diesel Exhaust Fluid (DEF) Modules

Bmw 335D Diesel exhaust fluid (def) modules

Starting at $392.95, the Bmw 335D DEF module controls the delivery, heating, and dosing of diesel exhaust fluid into the SCR system to reduce NOx emissions. With 1 options in stock from Bosch, choosing the right replacement matters — a failed DEF module triggers warning lights, forces derate mode, and can eventually prevent the engine from starting.

Signs your Bmw 335D DEF module is failing

  • DEF warning light or 'Check Emissions System' message appears on the dash even with a full DEF tank
  • Engine derate warning: power is reduced or vehicle is limited to a low top speed by the ECM
  • DEF fluid is not being consumed at a normal rate, suggesting the dosing pump or injector is not firing
  • Frozen or unreliable DEF level readings caused by a failed tank heater circuit inside the module
  • Fault codes stored for DEF pump pressure, DEF quality sensor, or DEF heater (e.g. P20EE, P203F, P204F series)
  • Engine cranks but will not start after repeated DEF system warnings have been ignored and the ECM has enforced a no-start lockout

Which DEF module should you buy for your Bmw 335D?

The DEF module is often sold as a complete assembly — pump, heater, level sensor, and quality sensor combined — but some applications separate the pump from the tank-mounted sensor unit. Match the part to exactly which component your diagnostic codes point to, and confirm OE part number compatibility for your Bmw 335D's emission tier, because EPA regulations changed module design across model years.

OE-Equivalent Complete DEF Assembly
Best for
Vehicles where the pump, heater, and sensors are integrated into one tank unit
What you get
Drop-in fit, all sensors pre-calibrated, least diagnostic risk after install
DEF Pump Module Only
Best for
Cases where fault codes isolate failure to the dosing pump and the tank-mounted sensor is confirmed good
What you get
Lower cost repair targeting confirmed pump failure; tank sensor reused
DEF Tank Sensor / Quality & Level Sensor
Best for
Fault codes pointing specifically to DEF quality, temperature, or level signal with pump pressure confirmed normal
What you get
Standalone sensor replacement; requires draining DEF tank for access
Remanufactured DEF Module
Best for
Budget-conscious repairs on higher-mileage Bmw 335D where OE pricing is prohibitive
What you get
Rebuilt to OE spec, core charge typically required, verify warranty length before buying

Diesel exhaust fluid (def) modules brands we stock for your Bmw 335D

Bosch
1 option · from $392.95

Replacing the DEF module on a Bmw 335D

Moderate⏱ 1–3 hoursSocket and ratchet setDEF-safe drain container and hand pump for fluid removalTorx or specialty bit set (varies by Bmw 335D)OBD-II scan tool capable of emissions system codesNitrile gloves and eye protection

Begin by draining the DEF tank using a hand pump to avoid spills, then disconnect the electrical connectors and fluid lines from the module before unbolting the assembly from the tank or chassis mount. DEF is corrosive to certain metals and irritating to skin, so gloves and eye protection are essential throughout. After installing the new module, refill the tank with certified DEF, clear stored fault codes with a scan tool, and run the engine to confirm the system pressurizes and no new codes return.

Frequently asked questions

How much does it cost to replace a DEF module on a Bmw 335D?
Parts start at $392.95 for the Bmw 335D DEF module. A complete OE-equivalent assembly costs more than a pump-only or sensor-only replacement. Add one to three hours of labor at a shop if you are not doing it yourself. Remanufactured units can reduce parts cost but may carry a core charge.
Can I drive my Bmw 335D with a bad DEF module?
Not for long. The ECM on a diesel with a failed DEF module will issue escalating warnings and then enforce an engine derate, reducing power significantly. After enough ignored warning cycles the system can trigger a no-start lockout. Continuing to drive risks permanent SCR catalyst damage and potential failed emissions inspection.
Will a faulty DEF module throw a check engine light on my Bmw 335D?
Yes. A failing DEF module typically stores one or more OBD-II or manufacturer-specific fault codes — commonly in the P20xx range — and illuminates the check engine or emissions warning light. A scan tool that reads emissions-related codes is necessary to confirm whether the pump, heater circuit, quality sensor, or level sensor is at fault before ordering parts.
How long does a DEF module last on a Bmw 335D?
DEF modules typically last many years under normal use, but lifespan is affected by DEF fluid quality and contamination. Using non-certified DEF or allowing the tank to run completely dry repeatedly can accelerate pump wear and corrode the quality sensor. Vehicles operated in very cold climates may see earlier heater element failure.
Does the DEF module need to be programmed after replacement on a Bmw 335D?
Most bolt-on DEF modules do not require programming, but some Bmw 335D applications require the replacement unit to be initialized or calibrated with a scan tool after installation so the ECM recognizes the new assembly and clears adaptation data from the failed unit. Check the specific fitment notes for your Bmw 335D before assuming a straight swap is sufficient.
What happens if I use poor-quality DEF fluid in my Bmw 335D?
Contaminated or substandard DEF fluid is a leading cause of DEF module and SCR catalyst failure. Low-quality fluid can clog the dosing injector, corrode the quality sensor, and leave crystalline deposits in the pump. Always use ISO 22241-certified DEF and replace the fluid if it has been stored improperly or is past its shelf life.

Shop diesel exhaust fluid (def) modules by year for the Bmw 335D

20112010

More parts for your Bmw 335D

Auxiliary Engine Cooling Fan AssemblyAir / Fuel Ratio SensorStrut BumperControl Arm Bushing KitBrake Pad & Rotor KitA/C Compressor KitWheel Bearing KitDisc Brake Caliper Guide Bushing Kit

Diesel exhaust fluid (def) modules for other Bmw models

Bmw X5