This post is part of our “Deep Delve” series, where we’ll focus on one part at a time. The goal of these posts is to provide our customers with the knowledge they need to make informed decisions about their vehicle. We can’t reveal all the knowledge we have about these parts, but hopefully the information below will help you find the issue in your vehicle.
What is a Differential Electronic Module (DEM)?
A previous blog post went into more detail about the functions of a DEM, but in short, the Differential Electronic Module (DEM) plays a crucial role in the performance and drivability of all-wheel-drive (AWD) vehicles. Despite its importance, this module is often overlooked during diagnosis because it doesn’t always post clear trouble codes in these year/models.
This module is found in the following P2 platform Volvo vehicles:
- 2005–2011 Volvo S40
- 2003–2009 Volvo S60
- 2004–2012 Volvo S80
- 2005–2011 Volvo V50
- 2003–2010 Volvo V70
- 2010–2012 Volvo XC60
- 2003–2010 Volvo XC70
- 2003–2010 Volvo XC90
Common Symptoms of a Faulty DEM
The DEM can be particularly tricky to diagnose. It may fail silently, without triggering specific DTCs (Diagnostic Trouble Codes). However, these are some of the most common symptoms:
- Intermittent or complete loss of AWD
- Communication errors on the high-speed CAN network
- No start conditions due to CAN bus interference
- Inability to communicate with the DEM via scan tool
- Interference with other module communications
Common Diagnostic Codes which may indicate a DEM Failure
- DEM-000B – Oil pressure, incorrect value
- DEM-000C – Control module, faulty hardware
- DEM-0001 – Temperature sensor, faulty signal
- DEM-0002 – Pressure sensor, faulty signal
- DEM-0005 – Control valve, internal fault
- DEM-0006 – Feed pump, faulty signal
- DEM-0007 – Hydraulic pressure, incorrect value
- DEM-0008 – Control module, calibration fault, internal fault
- CEM-1A64 – Communication with DEM missing
Like all DTCs, presence of these codes does not definitively mean the module is faulty. Thorough diagnostics should always be performed.
These codes may appear intermittently or may not post at all. DEMs can cause interference on the high-speed CAN network which prevents scan tools from reading each module.
Why the DEM Fails: Water Damage and Overload
The DEM’s mounting location makes it extremely vulnerable to water intrusion, especially in climates with snow, rain, or road salt. Over time, this can lead to severe corrosion, short circuits, and total module failure.
In many cases, the Haldex pump can clog, draw too much current, and short the DEM internally. This is why XeMODeX strongly recommends replacing the pump anytime the DEM is serviced.
Why Replacing the DEM is Difficult
While these DEMs aren’t VIN-coded to your vehicle, there are many different software packages. Replacing with a used DEM is technically possible, but without knowing the software packages it’s very unlikely the software will be a match. Replacing with a non-matching DEM could lead to further problems.
The XeMODeX Remanufacturing Advantage
At XeMODeX, we completely remanufacture the DEM with long-term durability in mind. Here’s what sets our process apart:
- Thorough Inspection and Diagnosis – Every unit is tested on our proprietary testing platform that simulates real-world driving conditions.
- Component-Level Repairs – Faulty internal components, including damaged circuits or chips, are replaced.
Preventative Engineering Improvements – We upgrade vulnerable areas of the module’s design to prevent repeat failures.
Low-Viscosity Silicone Coating – To prevent future water intrusion, the entire DEM is coated with a protective silicone barrier.
Replacement Hardware Available – For units with severe water damage beyond repair, XeMODeX can offer replacement hardware with the same reliability and protection.
Don’t Forget the Haldex Pump
One of the most common causes of DEM failure is a clogged or failing Haldex pump. When the pump draws too much current, it can instantly damage even a freshly rebuilt DEM. Whenever we rebuild a DEM, we highly recommend replacing the pump at the same time to protect your investment.
Need Your DEM Repaired?
Whether your Volvo is experiencing intermittent AWD issues or is completely down due to a failed DEM, XeMODeX is your go-to source for a dependable and lasting solution.
United States Customers: https://xemodex.com/us/product/differential-electronic-module-for-volvo-repair-service/
Canadian Customers: https://xemodex.ca/ca/product/differential-electronic-module-for-volvo-repair-service/
Final Thoughts
If you own a P2 platform Volvo with AWD, the Differential Electronic Module (DEM) is something that shouldn’t be ignored. Whether you’re dealing with strange CAN network issues, a failed AWD system, or no start conditions, the DEM could be the root cause, even if no code points to it.
XeMODeX’s enhanced remanufacturing process not only repairs but protects your DEM for the road ahead.
