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 Central Electronic Module (CEM)?
A future blog post will delve deeper into the role of the Central Electronic Module (CEM), but in short, it functions as a “smart fuse box,” managing key electrical and communication systems. As one of your vehicle’s most critical modules, any CEM-related issues should be addressed promptly. These modules are prone to failure, and replacing them can be complex due to vehicle-specific programming requirements. Below, we’ll cover common faults, symptoms, and how XeMODeX offers reliable solutions.
This part is found on the following Volvo models:
- 2001 – 2004 Volvo S60
- 1999 – 2004 Volvo S80
- 2001 – 2004 Volvo V70
- 2001 – 2004 Volvo XC70
- 2003 – 2004 Volvo XC90
Common CEM Faults and Symptoms
Certain Central Electronic Modules (CEMs) are prone to overheating, which places excessive stress on the circuit board and its components. Over time, this can lead to issues with the vehicle’s CAN (Controller Area Network) system. One of the earliest signs of CEM failure often presents as a problem with the Driver Information Module (DIM). As the CEM deteriorates, communication within the CAN network becomes erratic, causing the gauges and displays in the DIM to malfunction. While these symptoms may initially seem like a DIM failure, they are frequently linked to a faulty CEM. This issue is particularly common in 2004 models equipped with CEM hardware part number 8688513.
When this type of CEM overheats, it will usually affect the low-speed network first, resulting in:
- Loss of communication with the modules on the low-speed network
- Windows not working properly, either not rolling up or not rolling down
- Power seats not working
- Climate function not working
- Remote lock/unlock not working
- DIM gauges bouncing erratically or not working at all
- Sunroof not working
If the CEM gets bad enough, it will start affecting the high-speed network as well, resulting in:
- Loss of communication with the modules on the high-speed network
- ABS warning lights displayed in the cluster
- “Emergency Brake Service Required” message displayed in the cluster
- Speedometer and/or Tachometer will stop working intermittently or permanently
- Transmission warning message displayed in the cluster
- Loud “clunk” from the transmission
- The vehicle not starting
- Complete loss of communication with the vehicle.
Other symptoms include:
- Starter Motor not working, even though start is approved by the immobilizer sequence.
- Turn signals not working at all or one side turned on continuously.
- Headlight failures, including high beams, low beams, and/or fog lights.
- Horn not working at all.
- Wipers not working or stuck in high speed.
- Fuel pump relay not engaging.
- Battery drain, caused by the CEM not going to “sleep”.
Common Diagnostic Codes Indicating CEM Failure:
Please note the presence of these codes (minus the internal fault codes) does not necessarily mean your CEM is faulty. These are some of the common codes seen in the faulty CEMs we’ve worked on over the years. Thorough diagnostics should always be performed prior to working on a module.
- CEM-1D02, CEM-1D07, CEM-1D08, CEM-1D09 – Control Module Internal Fault
- CEM-DF13 – CAN-H, high speed network. Signal too high
- CEM-DF16 – CAN-L, high speed network. Signal too low
- CEM-6C48 – Transponder type. Faulty signal
- CEM-6C49 – Transponder communication. Faulty signal
- CEM-8F05 – Hazard warning signal switch activated too long
- CEM-8F04 – Turn signal lamp. Faulty signal
- CEM-8F12 – Low beam relay faulty
- CEM-8F22 – High beam relay faulty
- CEM-8F2F – Turn signal relay faulty
- CEM-3F90 – Fuel pump relay short to ground
- CEM-8F52 – Headlamp wash/wipe relay signal missing
- CEM-8F21 – Windshield wiper faulty signal
- CEM-DF17 – Communication with the SWM (Steering Wheel Module) missing
- CEM-9C03 – Antenna / light ring signal missing
- CEM-1A51 – Communication with the SRS Module (Supplemental Restraint System) missing
- CEM-1A52 – Communication with the DDM (Driver Door Module) missing
- CEM-1A53 – Communication with the PDM (Passenger Door Module) missing
- CEM-1A54 – Communication with the PSM (Power Seat Module) missing
- CEM-1A55 – Communication with the CCM (Climate Control Module) missing
- CEM-1A56 – Communication with the DIM (Driver Information Module) missing
- CEM-1A5F – Communication with the ECM (Engine Control Module) missing
- CEM-1A62 – Communication with the TCM (Transmission Control Module) missing
- CEM-1A64 – Communication with the DEM (Differential Electronic Module) missing
- CEM-1A5D – Communication with the REM (Rear Electronic Module) missing
- CEM-1A5E – Communication with the UEM (Upper Electronic Module) missing
- CEM-1A5F – Communication with BCM (Brake Control Module) missing
- And more
Why Replacing the CEM is Difficult
CEM issues are common, but replacing the module isn’t straightforward. The CEM is programmed specifically to each vehicle, meaning that simply swapping in a used unit—even with matching part numbers—won’t work. A new unit requires special scan tool programming, making it costly and inconvenient.
Part Numbers We Service
For your reference, here are some of the part numbers we’ve worked on:
8645716, 8645719, 8688434, 8688436, 8688513, 30657629, 9494336, 9494594, 8645171, 9452553, 8645205, 9452596
Don’t worry if your part number isn’t listed. We’ll still be able to help!
XeMODeX Solutions for CEM Failures
At XeMODeX, there are two services we offer for this part:
- Program Transfer Service to a XeMODeX supplied unit – We transfer your CEM’s programming to one of our remanufactured CEMs, giving you a warranty on the hardware, and some extra confidence that you’ll be getting good hardware reinstalled into your vehicle.
If you’re in the USA, click here: https://xemodex.com/us/product/central-electronic-module-for-volvo-program-transferservice/
If you’re in Canada, click here: https://xemodex.ca/ca/product/central-electronic-module-for-volvo-program-transferservice/
If you’re outside the USA and Canada, please contact our customer service team at 1-888-712-2525 or email sales@xemodex.com
2 Program Transfer Service to a Customer supplied unit – We transfer your CEM’s programming to a good used matching CEM you supply, which is ideal for mechanics who may already have a good used unit.
If you’re in the USA, click here: https://xemodex.com/us/product/central-electronic-module-for-volvo-program-transfer-service/
If you’re in Canada, click here: https://xemodex.ca/ca/product/central-electronic-module-for-volvo-program-transfer-service/
If you’re outside the USA and Canada, please contact our customer service team at 1-888-712-2525 or email sales@xemodex.com
Things to keep in mind
- If your vehicle isn’t starting due to an immobilizer failure, we’ll need your Central Electronic Module (CEM), Engine Control Module (ECM), and at least one key. This will allow us to test the immobilizer function on our test bench.
- The vast majority of CEMs we service are plug-and-play upon return, requiring no additional programming. However, in rare cases, a software reload may be necessary in the vehicle after reinstallation. While this is an exceptionally uncommon occurrence, we believe in full transparency—so while highly unlikely, we cannot guarantee with 100% certainty that a software reload won’t be required.
Why Choose XeMODeX?
- Cost-Effective Alternative to New CEM Replacement
- No Need for Dealership Programming
- Plug-and-Play Solutions
- Industry-Leading R&D and Repair Expertise
If you’re experiencing CEM-related issues in your Volvo, XeMODeX can provide a reliable and effective solution. Contact us today to learn more about our services!
Visit www.xemodex.com to check out our products and services.
