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Engine code

N43B16 engine faults.

The listing only gives the engine code.

unknown

fuel

1597 cc

displacement

90 kW (122 HP)

power

3 fault write-ups. All are important.

Before you buy

Known faults

3 important faults

critical2

Electric water pump: silent failure, immediate overheating

critical

In these engines the water pump is not belt driven but has its own electric motor. It gains on fuel consumption, but it opens a new failure path: the pump or its electronics often simply stops with no warning. Measured in the official complaints, the typical mileage is 161,000 km (a tenth of the complaints already at 81,000, a tenth only above 257,000 km). So the common wisdom of "around 100,000 km" is early: most of the failures happen between 130,000 and 250,000 km.

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With a belt driven pump the flow weakens gradually, here the circulation stops in an instant. In urban traffic the temperature crosses the limit within minutes, the cylinder head distorts, and the repair is an engine rebuild.

Replacing a still good pump at around 120,000 to 150,000 km costs less than repairing an overheated engine. If the replacement is already in the service book, the pump has already been changed.

between 81,000 and 257,000 km

What to check

  • Watch the coolant temperature gauge after startup: it should settle evenly, not jump around
  • Standing still with a warm engine, listen for whether the cooling fan and the pump are working
  • Ask for a fault code read: codes pointing at coolant flow belong here
2 more steps in the write-up

N43: plastic chain guide breaks and the debris blocks the oil pickup

critical

On the N43 direct injection four cylinder the plastic guides of the timing chain can break. The broken pieces fall into the sump and block the screen of the oil pickup. From then on the engine is starved of oil, and that takes out the bearings first.

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If the chain is rattling, the debris may already be on its way to the oil pickup, so leaving the replacement for later is not enough.

On the same engine the injectors, the ignition coils and the NOx sensor can fail too.

What to check

  • Identify the engine first: a 320i/318i from 2005 to 2011 can be an N46 (port injected) or an N43 (direct injection). If the version does not show which engine is fitted, the build date and the engine number decide. The N43 arrived in 2007, and this fault applies only to the N43
  • On a cold start listen to the front of the engine: rattling or clicking from the timing chain
  • Ask whether the oil pressure light has ever come on, even for a moment
3 more steps in the write-up

expensive1

N43 / N53 lean burn petrol: injectors, ignition coils, NOx sensor

expensive

The N43 (four cylinder) and the N53 (six cylinder) are direct injection petrol engines built for lean burn operation. Lean burn demands far more of the injection system than a conventional port injected design, and these are exactly the three parts that gave trouble in service: the injectors, the ignition coils and the NOx sensor.

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You notice this as a rough, uneven idle, hesitation on a cold start, loss of power and higher fuel consumption. A faulty NOx sensor on its own also raises consumption, because the control unit then fuels for the worst case.

The piezo injectors are expensive each, and when one fails the replacement rarely stops at one. The N53 also uses the same high pressure pump as the N54, where pump failures led to litigation in the USA. Pump failures were reported on the N53, but it is not known whether they are as frequent as on the N54 (the N53 was not sold in the USA, so there is no official complaint data on it).

What to check

  • Identify the engine first: a 320i/318i from 2005 to 2011 can be an N46 (port injected) or an N43 (direct injection). If the version does not show which engine is fitted, the build date and the engine number decide. The N43 arrived in 2007, and this fault applies only to the N43
  • After a cold start listen to the idle for at least a minute: shaking, misfire, fluctuating revs
  • Ask for a fault code read specifically for misfire (per cylinder) and for the NOx sensor
4 more steps in the write-up

Engine code

Factory data

Factory data

Engine family
—
Fuel
unknown
Displacement
1597 cc
Power
90 kW (122 HP)
Production
—

Generations

Which models it is fitted to

1 generations.

Information, not an expert opinion

We write the descriptions, and we put the source next to them. A person reviews them before they go out. They are still information, not a technical expert opinion.

  • A fault on the list does not mean the car you are looking at has it.
  • A fault missing from the list does not mean the model is fault-free. Write-ups are made model by model. Not all of them are done.
  • You decide whether to buy. This is no substitute for an inspection. That needs a workshop and a history check.
Details in the terms