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Model specific boards => Golf mk4 => Topic started by: RhosneigrGaz on 04 February 2012, 19:54

Title: Temp/MPG fault
Post by: RhosneigrGaz on 04 February 2012, 19:54

I hate people posting without searching/researching but i'm a little stuck...

Got car last week, 106,000 miles and seems well looked after.

However its running cold 70-80c, idling like a b!tch 500-2000rpm, engine management light on and 25mpg driving slowly.

Now i'm expecting it to be a MAF or Lamda but have read a thermostat and temp sender will cause low MPG?

Why is this? anyone explain it to me?

Gonna get my own VAG COM check tool thing having read a post tonight on it and see what it throws up!!

Title: Re: Temp/MPG fault
Post by: richw911 on 04 February 2012, 20:11

Could be a mix of things but yeah the temp sender could well be gone.

http://www.golfgtiforum.co.uk/index.php?topic=88088.0

When you have the reader you need to scan the car then drive it and see which codes if any reappear

Title: Re: Temp/MPG fault
Post by: Wayne on 04 February 2012, 21:24

Sounds like a knackered temp sender.

Title: Re: Temp/MPG fault
Post by: RhosneigrGaz on 04 February 2012, 21:26

Appreciate ur help guys

Ordered the VAG COM reader, gonna order the temp sender/stat also, as i plan to keep the car 3-5 yrs its worth doing whatever!!!

Thanks!

Title: Re: Temp/MPG fault
Post by: richw911 on 04 February 2012, 21:27

Quote from: RhosneigrGaz on 04 February 2012, 21:26

Appreciate ur help guys

Ordered the VAG COM reader, gonna order the temp sender/stat also, as i plan to keep the car 3-5 yrs its worth doing whatever!!!

Thanks!

TBH they are both very common faults and for the price you are wise to replace them  :smiley:

Title: Re: Temp/MPG fault
Post by: golf-sib on 04 February 2012, 22:52

Temp sender is very easy to do, open rad valve up, drain some coolant, I  usually remove airbox  to make it a lot easier to work with and its one clip out, sensor pulls out (collant will poor out when sensor is removed unless you drained some coolant), new sensor in, clip in and wollah

But it does sound like temp sensor

Title: Re: Temp/MPG fault
Post by: RhosneigrGaz on 10 February 2012, 15:54

Got me fault code reader which lit up like a frikin Xmas Tree!!!!
Cleared the faults and fitted new sensor, still no joy, so gonna do the stat in the week.

Amazing what the fault code reader showed up:

16486 -          Maf - Signal too low - NEW MAF TIME
16684-85-86 - Random Misfires      -  Keep an eye on this
17544 fuel trim bank (add) system to lean , p1136-35-00 - Investigate hose boost leaks
17704 - Error in mapped Cooling system - Hope that green sender and stat sort this
17705 - Pressure drop between turbo and throttle valve - Clean Throttle body and investigate boost leaks
17956 - Boost pressure regulation valve N75 - Check wiring to N75 and maybe replave N75

Plenty to be getting on with but nothing major i hope


Again as i plan to keep it gonna do a full plugs and filter change whilst i'm fidling next week...... FUN N GAMES Eh?

Title: Re: Temp/MPG fault
Post by: richw911 on 10 February 2012, 16:12

17705  :lipsrsealed:

Title: Re: Temp/MPG fault
Post by: RhosneigrGaz on 10 February 2012, 16:14

Quote from: richw911 on 10 February 2012, 16:12

17705  :lipsrsealed:

Spill the beans....

Title: Re: Temp/MPG fault
Post by: richw911 on 10 February 2012, 16:16

Quote from: RhosneigrGaz on 10 February 2012, 16:14

Quote from: richw911 on 10 February 2012, 16:12

17705  :lipsrsealed:

Spill the beans....

Boost leak that is a nightmare to find   :sad: However check the pancake pipe as is prone to leak there. Does it have the standard recirculating valve on it?

Title: Re: Temp/MPG fault
Post by: RhosneigrGaz on 10 February 2012, 16:20

Just read on the pancake, no idea what it is but i'll read up 2nite and check it in the morning.

Its 100% bog standard at the moment, but i get the feeling it's well overdue a service!

Gonna check for boost leaks, boring job but gotta be done!

Cheers for the help.

Title: Re: Temp/MPG fault
Post by: richw911 on 10 February 2012, 16:30

The standard plastic recirculating valves crack so check that out  :smiley: