MPG live monitoring

[MikeH]

I haven’t needed to use the forum for a while so I apologise for only contacting everyone when I have a problem. I normally have the MPG I am doing displayed all of the time. I have noticed last two trips the MPG I am getting is far less than usual. My CX5 is a diesel 2016 sports Nav. I have looked at the tyres and there is no obvious problems I will make sure the pressures are ok today. I cant believe the pressures being slightly out would cause the loss in MPG I am experiencing though. Has anyone experienced this, or got any advice that would explain/cure it.

[ROCKETRON]

Could be doing a regen. Also during the colder weather the average mpg drops by 2-3mpg. What figures are you seeing?

[MikeH]

Thanks for your reply Rocketron, I am getting really low live mileage sometimes below 10 MPG, i’ve Never noticed it that low before. My overall average is 47.2 MPG so I am expecting that to drop drastically while this persists. What does a regen do?

[ROCKETRON]

You are obviously using the instantaneous reading which in a normal journey will go from 5- 99 mpg and so is really quite useless. If you are doing a gentle cruise with light throttle and the instantaneous reading is 10mpg or low then the car is probably doing a regen.
This is done every 200-300 miles and lasts for about 15 mins or around 10-15 miles. After a regen the mpg goes back to normal. A regen involves the car injecting diesel on the exhaust stroke to heat up the exhaust and dpf to around 500C to burn off the particulate matter.  If you finish your journey before it’s finished then it will start again next time the car is up to temperature. Too many aborted attempts is what causes the oil to be diluted with diesel and cause the oil on the dipstick to look high.

[Willpower]

What does a regen do?

It might be worth your while reading through this.   http://mazdacx5forums.co.uk/index.php?topic=383.0

[MikeH]

Thanks for replies, I have only been doing really short journeys lately, will take it for a longer spin so the regen can complete.