Electronic diagnostics

5 min read

MINI COOPER S D F55

Tracing and fixing faults in electronic engine management systems

Rob Hawkins visits BMW MINI specialist Mad4Mini to discover the common problems that can arise on the F55 Cooper S diesel engine.

The F55-generation MINI was launched in March 2014 and has evolved with a confusing assortment of engines. Some have three cylinders, whereas others have four – the Cooper D is a three-cylinder diesel, whereas the Cooper S D we’re looking at is a four-pot. On paper, it appears to be the best one for performance and economy, boasting 168bhp at the flywheel, a 0-62mph time of 7.3 seconds and a frugal fuel economy of 70.6mpg.

We visited independent MINI specialist Mad4mini to follow them diagnosing an engine management light (EML) on a customer’s 2016 Cooper S D. They had recently replaced the diesel particulate filter (DPF) because it had become choked beyond rescue through short journeys. Some 1200 miles later and the vehicle was possibly beginning to show signs of a blocked EGR cooler and valve.

Unfortunately, emission-related issues caused by a build-up of carbon are a common issue on many diesel engines, which are best fixed by long motorway runs where the engine has a chance to get up to temperature and burn off that unwanted debris. Mad4mini had owned such a car and found no problems with it because it spent a couple of hours a day on the motorway.

Typical MINI F55/F56/F57 COMPONENTS

1 The OBDII port is on the inside of the offside A-post. Open the driver’s door (on a 1 RHD model) and look for a plastic flap that’s labelled OBD. Use a small screwdriver to carefully prise the flap open on its right edge (it’s hinged on the left side) to reveal the port.

**2 It’s worthwhile removing the upper engine cover. It’s only secured with a few locating lugs, but may need a little leverage around its edges to help release it and avoid breaking the plastic.**

3 The vehicle battery is hidden under a cover in the nearside rear of the engine bay. There’s a solitary red plastic cover for connecting a backup to the positive terminal, which is worth doing if you are connecting a fault code reader – it helps to reduce the risk of anomalies through voltage drops.

**4 A mass airflow (MAF) sensor is fitted to the induction outlet on the side of the air filter housing on the nearside of the engine bay. Mad4mini says this sensor appears to be reliable.**

**5 Tucked below the offside of the air filter housing is the shiny exterior of an EGR cooler. The EGR valve is also near here and both components can become choked with carbon – see Fault 1.**

This article is from...

Car Mechanics Magazine

18 August 2023

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