This BMW 5 Series came in with a Drivetrain warning on the dash and some shaking in sport mode. Our computer diagnosis found a misfire, so we replaced all four spark plugs and ignition coils. The warning came back, with a lack of power and shaking at traffic lights. We replaced all four fuel injectors next. Then we found the new spark plugs had already turned black and the engine oil was low. Our team suspected oil was getting into the spark plug area and replaced the valve cover assembly.
Job completed: September 2026
| Car | BMW 5 Series |
|---|---|
| Symptom | Drivetrain warning and shaking in sport mode; later a lack of power and shaking at traffic lights |
| Fault found | Misfire fault on our computer diagnosis. After new plugs, coils and fuel injectors, the new plugs had turned black and the engine oil was low. Our team suspected oil was getting into the spark plug area, most likely past the valve cover. |
| Repair done | First visit: all four spark plugs and ignition coils. Second visit: all four fuel injectors, then the valve cover assembly, an engine oil top-up and another set of spark plugs. |
| Parts | New spark plugs and ignition coils, four fuel injectors and a valve cover assembly |
| Time taken | Two visits |
| Cost | Quoted before each stage of work |
| Warranty | Contact us for warranty details on the specific parts replaced |
The owner booked the BMW 5 Series in after a Drivetrain warning came up on the dash. The car was also shaking a little when driven in sport mode. The owner asked us to check it, and to see if anything else was due for maintenance.
After the first repair, the Drivetrain warning came back. This time the owner also felt a lack of power and some shaking while stopped at traffic lights. It was worse once the engine was warm.
The car is a BMW 5 Series, finished in dark grey. Its engine takes four spark plugs, four ignition coils and four fuel injectors, and we replaced each as a full set.
With a coil sitting directly on each plug, a weak plug or coil shows up quickly as a misfire or rough running.
On the first visit, our computer diagnosis showed a misfire fault, so we quoted all four spark plugs and ignition coils. After fitting them, our team test drove the car and checked it again by computer. All good.
When the Drivetrain warning came back, the computer still showed a misfire fault. The new plugs and coils checked out fine, so our team advised replacing the fuel injectors. Test drives after the injectors still showed a little shaking and a lack of power, though less than before.
Our team then checked the spark plugs again. The plugs fitted a few days earlier had already turned black. The engine oil was also low, so soon after the last service.
New spark plugs should not turn black within days. Together with the low engine oil, that told our team that oil was most likely getting into the spark plug area and fouling the plugs.
Our team listed three ways oil could get in: the valve cover, the valve seals or the piston rings. On a car this new, valve seals or piston rings were judged unlikely. Either of those would mean an engine overhaul. From experience, our team expected the valve cover, so we replaced the valve cover assembly first.
We quoted each stage before starting, and the owner approved each one.
From our team's record of this job. Number plates are pixelated.
This job was quoted in stages: first the spark plugs and ignition coils, then the fuel injectors, then the valve cover assembly. Each quote came before the work, and the owner approved each stage before we started.
The cost for your car depends on what the diagnosis finds. WhatsApp us your BMW model and what you are noticing, and we will quote before any work begins.
Change spark plugs on schedule, and check the engine oil level between services. If new plugs turn black soon after fitting, or the oil level drops faster than it should, have the car checked for oil getting into the spark plug area.
For the valve cover, the gasket is rubber and it will eventually harden and crack from heat cycling. There is no way to prevent this entirely, but catching the early oil smell and dealing with it promptly stops oil from reaching hot exhaust components and turning a simple gasket job into a bigger cleanup.
If your BMW is shaking, down on power, or showing a Drivetrain warning, have it checked.
This BMW 5 Series (Spark plug and valve cover replacement) was handled at 1 Car Service, an independent workshop in Sin Ming AutoCity, Singapore. For BMW, we use dealer-level ISTA diagnostics. We hold a 4.9★ rating from 1,836+ Google reviews.
WhatsApp us your BMW model, year, mileage and a short description of what you are noticing. We will tell you what is likely going on and what it will cost before any work begins. Every repair is road tested before you collect.
The cost depends on the engine variant and whether you replace just the plugs or include the ignition coils at the same time. Doing plugs and coils together in one visit is more cost-effective than returning separately for each item. WhatsApp us your BMW model and year and we will give you a clear number.
Common signs are a rough or uneven idle, hesitation when accelerating, a misfire warning light on the dash, or the car simply feeling less responsive than usual. If your plugs are overdue by mileage or have never been changed, it is worth having them inspected. If new plugs turn black soon after fitting, look for the cause, such as oil getting into the spark plug area.
The valve cover gasket is rubber. Over years of heat cycling, it hardens, shrinks and develops small cracks. Oil then seeps out past the gasket, which you often smell before you see it, especially when the engine is warm. On this BMW 5 Series, our team suspected oil was getting into the spark plug area, so we replaced the valve cover assembly.
Yes. We use ISTA, the BMW dealer-level diagnostic system, to read fault codes and check the engine control units on BMW vehicles. On this job, our computer diagnosis showed a misfire fault, and a check of the spark plugs showed the new ones had turned black.
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