2.0Tdi Poor MPG? Temp Sensor? VAG-COM advice? Which sensor?

[davidmbell]

Morning all, I have a 2007 A4 2.0 Tdi Cabrioloet - 2007 with poor MPG.

It's done 105,000 miles.

Ever since I bought it in Sept its had quite poor MPG and only now have I thought something might be up. I appreciate its a ****** heavy car, but not this bad.

Average around town is 33mpg, and on a long run - Leeds to Birmingham the other day 50-80mph it just averaged 46mpg.

I had noticed when I drove it home from the seller that the temp guage seemed to vary wildly and never sit comfortably at 90 degrees for any length of time. It would mositly sit somewhere just above 70 or at 80C give or take. Very ocasionally it would move to 90 (which is where I gather it should sit all the time).

I've read that this might be down to the ECU getting a duff temp from one of two sensors? The fuel temp sensor and coolant temp sensor.

So, couple of options I have access to a full VAG-COM - so if I use that what is it I am looking for in particular? I've only ever used it to mod a couple of things (teardrop wipe etc) and nothing 'advanced'.

Would VAG-COM show which sensor was duff? It doens't show any errors of that nature.

Finally, do I gather both sensors are identical? Could I buy one, try it in coolant spot and if no change try it in fuel slot? That make sense?

Thanks,

David

 

[studunc06]

both of them are identical mate, your MPG doesnt sound too different from mine but mine is a quattro though, but from what your saying i would go for the coolent temp sensor, if yours isnt a quattro then it shouldnt be too bad to do. you can pick them for a few quid.

 

[Audi33]

Morning all, I have a 2007 A4 2.0 Tdi Cabrioloet - 2007 with poor MPG.

It's done 105,000 miles.

Ever since I bought it in Sept its had quite poor MPG and only now have I thought something might be up. I appreciate its a ****** heavy car, but not this bad.

Average around town is 33mpg, and on a long run - Leeds to Birmingham the other day 50-80mph it just averaged 46mpg.

I had noticed when I drove it home from the seller that the temp guage seemed to vary wildly and never sit comfortably at 90 degrees for any length of time. It would mositly sit somewhere just above 70 or at 80C give or take. Very ocasionally it would move to 90 (which is where I gather it should sit all the time).

I've read that this might be down to the ECU getting a duff temp from one of two sensors? The fuel temp sensor and coolant temp sensor.

So, couple of options I have access to a full VAG-COM - so if I use that what is it I am looking for in particular? I've only ever used it to mod a couple of things (teardrop wipe etc) and nothing 'advanced'.

Would VAG-COM show which sensor was duff? It doens't show any errors of that nature.

Finally, do I gather both sensors are identical? Could I buy one, try it in coolant spot and if no change try it in fuel slot? That make sense?

Thanks,

David

Sounds like thats a bad temp sensor, mine had the same issue it decided to drop when it felt like it. After replacing the temp sensor the issues has now gone, mpg better than before too. Have a look at darkside developments online, i bought mine from there not expensive at all. Good luck hope you get it sorted

 

[davidmbell]

I took my previous A3 to Darkside and they were good - so might pester them as they'll no doubt help out in pointing me in the right direction as to where on earth the sensor is actually located! I don't know if this will work, but here's some pics of my temp guage posted on the cab group on FB https://www.facebook.com/groups/audicabriolet/permalink/10152564820930426/?comment_id=10152567031460426&offset=0&total_comments=24&notif_t=group_comment_mention

 

[GoneSouth]

A fluctuating temp needle isn't good - mine sits at 90 or just below and hardly moves. Sure sounds like a temp sensor issue.

Mpg at motorway speeds normally late 40s to early 50s depending who grabs keys first.
.

 

[davidmbell]

Spoke to Darkside they suggested thermostat before trying temp sensor.

Ordered genuine one from them but can't find any guides as to where the stat is?

If it's similar to the other vag tdi's it's in a sod of a location near the thermostat?

Anyone confirm?

2.0tdi BPW 140 engine

Thanks

David