BMW Glow Plug Replacement Guide BMW Diesel – Tips 2026
Changing BMW Diesel Glow Plugs – Complete Guide & Tips
Regardless of your BMW's age, the glow plugs will eventually fail. Like any diesel vehicle, your BMW has four glow plugs (six in six-cylinder models) that preheat the combustion chamber and make starting easier on cold mornings. BMW also uses a post-glow function that keeps the glow plugs running for a few minutes after starting – to reduce emissions.
Why replace faulty BMW glow plugs immediately?
Many BMW owners don't know this: In vehicles with a diesel particulate filter (DPF), a faulty glow plug prevents the regeneration of the DPF system. This can lead to expensive repairs to the particulate filter.
If you are not sure if a glow plug is faulty – read the error codes with our BMW diagnostic software and clear them after replacement.
Always change all glow plugs at once
A common mistake: only changing the faulty glow plug. This is not advisable – and here's why:
- Accessing the glow plugs requires removing several plastic covers – which takes a lot of time
- All glow plugs have been in operation for the same duration – the remaining ones will also fail soon
- Another replacement means a lot of effort again
Recommendation: Always replace the entire set when changing glow plugs. For BMW Diesel, we recommend glow plugs from the BERU brand – high quality and durable.
Stuck BMW Glow Plugs – How to Avoid Problems
One of the biggest challenges when changing glow plugs on a BMW Diesel is the risk of them seizing in the cylinder head. If they break off, either the cylinder head must be dismantled or a specialist must remove the plug on-site – both expensive and time-consuming.
Causes of stuck glow plugs:
- Carbon deposits between the glow plug body and the cylinder head
- Corrosion on the thread
Best Method – Soaking Glow Plugs Overnight:
Always assume that the glow plugs are stuck. The best method is to soak them overnight with a good penetrating oil:
- Kano Kroil – penetrates deep into the thread, dissolves carbon and corrosion (first recommendation)
- 50/50 mixture of ATF oil and acetone – very effective alternative
- 50/50 mixture of cola and vinegar – simple home remedy alternative
Step-by-step removal:
- Soak glow plugs overnight in penetrating oil
- Lightly tighten the plug first to loosen corrosion deposits on the thread
- Then slowly loosen with even pressure
- Gently rock the plug back and forth – never use force
- If resistance is met: stop the process and soak again
- While unscrewing, spray Brunox Turbo Spray into the thread – with every turn
Important: Do not use WD-40 – it is not suitable for loosening stuck glow plugs!
Recommended Penetrating Fluids for BMW Glow Plugs
- ✓ Kano Kroil – best choice
- ✓ Brunox Turbo Spray
- ✓ PlusGas Spray
- ✓ Liquid Wrench Penetrating Spray
- ✓ BG In-Force Penetrating Spray
- ✓ 50/50 ATF oil and acetone
- ✓ 50/50 cola and vinegar
- ✗ WD-40 – not suitable!
Installing New Glow Plugs – How to Prevent Future Problems
When installing new glow plugs, it is essential to lubricate the thread with high-temperature ceramic grease. This prevents them from seizing in the cylinder head later on. Conventional copper grease is not suitable for this purpose.
After Glow Plug Replacement – Clearing Error Codes
After replacing the BMW glow plugs, the error codes must be cleared with BMW diagnostic software to ensure proper operation. Use our BMW ISTA or INPA software for this – available for download immediately after purchase.