MajorCommonEngine

BMW 4 Series: N55 3.0T plastic charge pipe splitting under boost (435i)

N55 3.0T plastic charge pipe splitting under boost (435i) is a common engine fault on the BMW 4 Series on the 2013–2018 cars, and we rate it major. Putting it right costs $450 to $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 20 documented faults on the BMW 4 Series.

Vehicle: BMW 4 Series
Engine: N55
Years: 2013–2018
Fuel: petrol
System: Engine

This page covers the BMW 4 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 4 Series faults20 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Turbocharger yet. We would rather show none than show a picture of a different part.

What goes wrong

The 435i's turbocharged straight-six feeds the throttle body through a moulded plastic charge pipe. The pipe and its quick-release coupler go brittle in underbonnet heat and split, usually all at once and usually at full throttle. The engine loses all boost, drops into limp mode and will barely pull away — alarming, but not damaging, and the car is still drivable at low speed. There is no sensor on the pipe itself, so stored faults only say the boost pressure is implausible, which sends the unwary chasing turbochargers. Independents fit an aluminium replacement, which cures it permanently for less than BMW charges for the original plastic part.

What you would notice

Sudden loud whoosh or hiss followed by a total loss of power under acceleration
Engine warning light with an underboost or boost-plausibility complaint
Car drives normally off boost but refuses to accelerate
Whistling from the front of the engine on the intake side

How to check it

Where to look. Short pipe running from the intercooler outlet at the front of the engine to the throttle body on the intake side, sitting just above the front subframe.

This fault will not show on a gentle drive, so take the car onto an open road and use full throttle in third gear at least twice, up to legal speed. A healthy 435i pulls hard and cleanly to the top of the rev range; a hesitation, a bang of lost boost, or a warning light means the pipe. With the bonnet up and the engine idling, listen for a hiss or whistle from the front of the engine on the intake side. Ask whether the charge pipe has already been replaced and whether the replacement is metal, because a car with an aluminium pipe fitted has had this problem solved rather than postponed. Ask whether the engine has ever been remapped or tuned, since higher boost brings this on sooner.

Parts involved: Turbocharger.

What it costs to put right

$450 to $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 charge pipe been replaced, and was it a metal one?”
“Has the car ever gone into limp mode?”
“Has the engine ever been remapped or tuned?”

Now check the BMW 4 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.

Motronix technical article — 'BMW Charge Pipe Failure on N20, B48, N55, and B58 Engines'
JXL Performance — 'BMW 435i F32/F33/F36 Buying Guide'
Evolution Racewerks and VRSF N55 F30/F32 charge pipe application notes (335i/435i)
Engine Patrol — '12 Common BMW 4 Series Problems'

BMW 4 Series buyer questions

Is n55 3.0t plastic charge pipe splitting under boost (435i) serious on a BMW 4 Series?

We rate it major and common on the BMW 4 Series. The 435i's turbocharged straight-six feeds the throttle body through a moulded plastic charge pipe. The pipe and its quick-release coupler go brittle in underbonnet heat and split, usually all at once and usually at full throttle. The engine loses all boost, drops into limp mode and will barely pull away — alarming, but not damaging, and the car is still drivable at low speed. There is no sensor on the pipe itself, so stored faults only say the boost pressure is implausible, which sends the unwary chasing turbochargers. Independents fit an aluminium replacement, which cures it permanently for less than BMW charges for the original plastic part.

How much does it cost to fix on a BMW 4 Series?

$450 to $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 4 Series years are affected?

Our research records this fault on the 2013–2018 BMW 4 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.