Essential Guide to BMW Glow Plug Detection and Control Unit Replacement

BMW Glow Plug Control Unit & Glow Plug Replacement

When it comes to maintaining your BMW diesel engine, replacing glow plugs and the glow plug control unit is a critical task. Whether you're working on a B47 EURO6 or N47TU engine, ensuring that the correct steps are taken will help you avoid unnecessary damage to your engine and glow plugs. In this article, we'll break down the process of glow plug replacement, explain the importance of glow plug detection, and provide technical insights on how to get the job done right.

When you replace glow plugs or the glow plug control unit in a BMW, you must carry out a glow plug detection procedure. This process ensures that the control unit recognizes all the glow plugs and activates the correct data set. Failing to do so could leave the wrong settings in place, which may lead to malfunctioning glow plugs, engine performance issues, or even damage.

Key Steps Before Glow Plug Replacement
Before jumping into the replacement process, it's vital to take a few precautionary steps:

1. Warm Up the Engine: Heating the engine to operating temperature makes it easier to remove the glow plugs. Removing glow plugs from a cold engine can damage the thread in the cylinder head.
2. Use a Specialized Additive: Spray the glow plugs with "Exhaust Turbocharger Additive 83192362168" and allow it to sit for about 2 minutes. This helps loosen any residue or corrosion around the plugs.
3. Tightening Torque: When installing the new glow plugs, a tightening torque of 10Nm to 15Nm is ideal. Stick to the middle of this range to ensure secure placement without over-tightening.

BMW Service Functions for Glow Plugs
BMW’s advanced diagnostic system offers two key functions for glow plug service:

• Activating the Safety Data Set: Before replacing the glow plugs, use the BMW diagnostic system to activate the safety data set in the glow plug control unit. This ensures that the replacement process goes smoothly and safely.
• Glow Plug Detection: After replacing the glow plugs or the control unit, you must run the glow plug detection. This checks whether the control unit recognizes all glow plugs, if the correct glow plugs are installed, and whether the proper data set is activated.

Why These Service Functions Are Crucial
Failure to run the glow plug detection could result in the control unit using the wrong data set for the new glow plugs, potentially causing functional limitations or even damage to the glow plugs themselves.

Relearning and Adjusting Glow Plug Values
For certain BMW diesel engines, such as the B47 EURO6 and B57, it’s necessary to relearn the resistance values of the glow plugs after replacement. This can be done using the “Learn Glow Sticks” service function.

For B37 and B47 engines that are not EURO6-compliant, there is no need to perform a service function after replacing the glow plugs.

Glow Plug Types and Control Unit Data Sets
Different BMW engines use different types of glow plugs depending on the power variant and manufacturing date. For example:

• N57TU Engine: Uses BERU CGP ceramic glow plugs.
• N47TU Engine: Can use either BERU CGP (ceramic) or Bosch GLP5 (ceramic) depending on the production date.

The glow plug control unit contains data sets to manage each type of glow plug with the correct voltage profile. There’s also a safety data set that ensures all glow plugs receive power without the risk of damage, even if a fault is detected.

Detecting Glow Plug Types Automatically
The glow plug control unit automatically detects the type of glow plug installed during the next full heating cycle. However, it can only distinguish between metallic (BERU ISS) and ceramic (BERU CGP or Bosch GLP5) plugs.

In the case of a voltage fluctuation or if the signal for starter intervention is activated, the detection process stops. If the control unit detects more than one incorrect glow plug type, it activates the safety data set. For a single wrong type, the control unit excludes that specific plug from the current cycle.
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In some cases, you can initiate a test glow via the service function to check if all glow plugs are correctly identified. If the test fails, the safety data set will activate, protecting the engine and glow plugs from damage.

Glow Plug Detection – A Must for Proper Engine Function
BMW's advanced glow plug system is designed to ensure optimal performance and engine health. By following the correct steps during glow plug replacement and making use of the service functions in your BMW diagnostic system, you’ll guarantee that your engine operates smoothly and efficiently. Always remember to run glow plug detection after replacement, and be mindful of the glow plug types and their respective control data sets.