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BMW 3 Series: N54 / N55 3.0L electric water pump & thermostat failure (335i E90/E92/F30)

N54 / N55 3.0L electric water pump & thermostat failure (335i E90/E92/F30) is a common cooling fault on the BMW 3 Series on the 2007–2016 cars, and we rate it major. Putting it right costs $900 to $1,900 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 88 documented faults on the BMW 3 Series.

Vehicle
BMW 3 Series
Engine
N54 / N55
Years
2007–2016
Fuel
petrol
System
Cooling

This page covers the BMW 3 Series as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All BMW 3 Series faults88 documented faults on this model

What you are looking at

An annotated photograph of an automotive engine thermostat identifying the wax capsule and both disc valves.Example of the part — not this vehicle

A double-valve engine thermostat, labelled: the wax capsule is what sticks.

Dougsim · CC BY-SA 3.0 · Wikimedia Commons

What goes wrong

Turbo 335is (N54 and N55) use an electric water pump and electric thermostat that are wear items, commonly failing from around 80,000-120,000 km - sometimes much earlier. When the pump fails the car can overheat suddenly and drop to limp mode with no warning, risking head-gasket or worse damage if driven on. Specialists replace the pump and thermostat together as they tend to fail around the same time.

What you would notice

  • Overheating warning or sudden 'increased power available after cooling' message
  • Loss of power / limp mode
  • No or weak cabin heat
  • Coolant warning light

How to check it

Where to look. Electric water pump on the front/side of the 3.0L block; thermostat housing adjacent

  1. Ask when the electric water pump and thermostat were last done; on a car past ~100,000 km with no record, budget for it.

  2. Watch the temperature behaviour on a longer test drive and check for a coolant/thermostat code on a scan.

Parts involved: Water pump, Thermostat.

What it costs to put right

$900 to $1,900 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the electric water pump and thermostat been replaced, and when?”
  • “Has it ever overheated or gone into reduced-power mode?”

Now check the BMW 3 Series you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

  • bmwtuning.co – Common N55 Engine Problems (electric water pump)
  • Alex's Autohaus – Common Problems on the BMW N55 / N54 (water pump, thermostat)

BMW 3 Series buyer questions

Is n54 / n55 3.0l electric water pump & thermostat failure (335i e90/e92/f30) serious on a BMW 3 Series?

We rate it major and common on the BMW 3 Series. Turbo 335is (N54 and N55) use an electric water pump and electric thermostat that are wear items, commonly failing from around 80,000-120,000 km - sometimes much earlier. When the pump fails the car can overheat suddenly and drop to limp mode with no warning, risking head-gasket or worse damage if driven on. Specialists replace the pump and thermostat together as they tend to fail around the same time.

How much does it cost to fix on a BMW 3 Series?

$900 to $1,900 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which BMW 3 Series years are affected?

Our research records this fault on the 2007–2016 BMW 3 Series. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Ask when the electric water pump and thermostat were last done; on a car past ~100,000 km with no record, budget for it. Watch the temperature behaviour on a longer test drive and check for a coolant/thermostat code on a scan. Look here: Electric water pump on the front/side of the 3.0L block; thermostat housing adjacent