Hello again Tej - thank you for that info..
The air bag light being on wont have any effect on the mpg.
That is a point with the idle revs -if they are high or erratic - that can be a cause... make sure its ticking over at around 750 or so rpm... any thing higher than 900 means its either not set up right or you have an inlet air leak on the engine.
Given you have not fault lights on the dash for the engine management system, then its not likely you have any management fault codes - but it would be worth having them checked - just in case - as that can help you...
Re the plugs - when new plugs come in the box - often they need the gaps checking -and often mechs these days dont do it - not if they "look" right - but its important to have those checked...
Also - ensure the engine is running fine as it should - not rough / missing at all - if it is - that will cause high mpg.
Now - other than that - the basics, I will give you a check list that working through, your mech should be able to find and cure the cause of your high mpg - that is as follows for you:
|Air intake system/vacuum system - blockage |
|Engine management system - connections/wiring/relays |
|Condition of fuel/fuel filter |
|Fuel pump/connections |
|Fuel pressure/delivery rate/fuel pressure regulator |
|Intake air temperature (IAT) sensor |
|Throttle position (TP) sensor |
|Heated oxygen sensor (HO2S) |
|Throttle valve/sticking/linkage |
|Knock sensor (KS) |
|Engine control module (ECM)|
Working through the list as above, the problem should be found / cured as it will be one or more of those issues.
Best Rgds, MIKE.Let me know if you need anything more on this at all -
Please do click on the OK rating to Excellent ratings service for me now, Thank you for that... and you can get back to me anytime if you need / wish..
Best Rgds, MIKE. Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.