BMW e90 3 Series Faulty EGR Thermostats/Glow Plugs Resulting in Low MPG

The BMW e90 three-series was often the best-selling luxury vehicle in Canada and the United States during its manufacturing period of 2006-2012. Many drivers are particularly fond of the 320d model for its efficient yet peppy diesel engine. Unfortunately, one of the common problems in the e90 diesel 3-series cars is a faulty EGR thermostat and glow plugs, which can result in significantly low miles-per-gallon (MPG) performance.

The average coolant temperature for the e90 series should be about 90 degrees Celsius or 195 degrees Fahrenheit. This results in an average MPG of about 35-45 for city driving. But with a faulty EGR thermostat, the BMW may be reading as low as 68 or 72 degrees Celsius. This will result in lower MPG. However in some cases, the vehicle may be reporting very high MPG when the actual MPG is quite lower. In either case, the cause of the problem is likely a malfunctioning EGR thermostat or glow plugs. A certified, independent BMW specialist can identify the problem and remedy the situation.

If you are driving one of the three-series e90 320d BMW’s, you may have a glow plug warning light come on for a brief period, prior to the engine warming up. Be aware of this problem, as it could lead to the glow plugs snapping off. These glow plugs control the emissions of the engine, and therefore the MPG as well as its environmental impact. They can be replaced by some everyday mechanic, but due to the complexities of a BMW engine, it is wise to contact a specialized BMW technician to solve the problem.

Search for a local, independent BMW repair shop with BMW mechanics that have dealer-level expertise at a fraction of the expense.