Volvo V50 Losing Fuel Efficiency – Reduced MPG

I have a Volvo V50 1.6 Eco Drive.  Over the past few months, it has started to lose fuel efficiency dramatically.  It dropped below 52 MPG and ended up around 42 MPG.  It turned out that this is caused by a semi blocked diesel particulate filter.   This was probably blocked because of soot caused by having dirty injectors.  I bought a bottle of DPF Cleaner  and also some Injector Cleaner and added them to the fuel.  I did it over two half full tanks.  I found that the MPG increased dramatically over the period of about 2 weeks.

The other potential diagnosis for this problem is a dirty MAS (Mass Airflow Sensor).  You can get this cleaned also.

If you are in the UK then I recommend visiting Halfords and getting them to clean your diesel particulate filter in a liquid.

Volvo V50 Reduced Engine Performance

I wrote this article back in 2013.  Since then I’ve owned two Volvos.

The bad news is that both Volvos that I’ve had this problem.  All the problems I’ve had have been caused by the diesel particulate filter and EGR valve.  Something goes wrong with the ERG value or a pipe get blocked and then soot builds up in the system.  Then the whole thing clogs.  You really need to get it fixed because otherwise your diesel particulate filter can block or worst case, you can block up the turbo charger.

The good news is that Volvo now admit they have a fault with these parts.  You should take your car to a Volvo garage and most likely they will replace and fix the problem for you.   The only problem with this plan is that Volvo will try to only fix the original fault and don’t want to take responsibility the damage caused by the fault.  You need to push the garage very hard to take responsibility and not charge you.


Here is my original post:

I purchased a Volvo V50 estate (secondhand) just over a year ago. After a few months it started having problems when pulling away or when revving the engine over 3,000 RPM. This first started happening when it was really cold (-9’C)… however, after a while, the car would often go into reduced engine performance mode at any temperature if pushed hard. This was really dangerous because this would often happen when joining a busy road or when trying to get out of a tricky situation. The car would then stall or loose most of the power. I wish Volvo would allow me to override this setting on the car so that I could remain safe.

Having spoken to several mechanics and researched on the internet – the problem generally seems to be with the particulate filter. It can be either a faulty cable (next to the battery) or the tube to the particulate filter sensor becoming blocked.

In my case, it turns out to be the tube to the particulate filter sensor becoming blocked. It seems that the Volvo dealer who serviced the car previously had not checked or topped up the EOYLS tank. This meant that the EGR (Exhaust Gas Recirculation) Valve that a pipe to the particulate sense and valve had become clogged up

The moral of this post is:

1) If I had taken the car to a garage when this problem first appear then it’s very lightly that the EGR valve would not become clogged and needed replacing.

2) Volvo know that this is a problem and should provide a sensor to the EOYLS tank.

3) Volvo should allow the driver to override the “Reduced Engine Performance” stalling and shutting down of the car. It is simple dangerous.