Morning All

Late last year the diesel heater coil light on the dash took to staying on for the maximum period of time, because of the time of year I thought it was normal until we got a second diesel octavia and that didn't do it.

A quick butchers on here and a session with VAG-COM and it comes up that the temperature sender is duff.

I purchased a new one from Jorily, slapped it in an all was fine - this was probably February this year.

In the last week the diesel heater light has started staying on for the maximum time, and now I have also noticed that the car is revving higher after starting, the first notch after 10, can't recall if that's 11 or 12. Usually it idles at the first notch below. After a several minutes it drops down to the normal idle, but it doesn't seem to matter if you drive hard, slowly, or sit around it seems to be taking the same time.

I haven't had a chance to connect the VAG-COM up - busy moving, but everything seems to point to a iffy temperature sender again so the computer is running on default settings (maximum heater time, then higher revs simulating something like the choke being open.

Anyone any thoughts?

Tom

Next time buy a genuine VAG temp sender.

Next time buy a genuine VAG temp sender.

That is what I was thinking. Unless of course the CTS is just masking some other problem....

Just spoken to TPS, they want £28.60 + VAT, that sounds about right?

Tom

Just spoken to TPS, they want £28.60 + VAT, that sounds about right?

That sounds about right cf my local dealer.

What colour is the one you got from Jorily?

If the sensor is faulty, then why not contact us and we can replace it. It's quite simple. All the parts we sell are OEM parts and are fully guaranteed for 12 months.

What colour is the one you got from Jorily?

Green

Tom

Green is the later version (early black ones were known to fail). I thought that Green ones as a rule were generally ok. But as with Jorily above, see if they will do a replacement.

Having discussed with Jorily/Graham the manufacturer of the replacement item I purchased was Febi Bilstein, who are the OEM supplier.

It seems therefore that if as suspected the sensor is at fault, then I am simply unlucky.

I'll check for codes tonight and take it from there.

Tom

I think you may have a wiring fault as the CTS usually only causes the ECU to throw a code when it's a bad connection or an open circuit.

I've been running a cheapo ebay one for the last 2 years, was 3quid...

I've been running a cheapo ebay one for the last 2 years, was 3quid...

Queue immediate failure

oh no not another £3

Best couple in as spares

Just try unplugging the connector to the existing sensor and then plugging it in again. You may find this will temporarily fix the problem. I replaced quite a few bad connectors.

OK, finally found my VAG lead, plugged it in yesterday, by jove was it cold sat there with the door open, frost on the car!

Anyway, fired the car up, read the details, no sign of an error under engine!

So it's not reporting a sensor error, there's none logged, but it's still doing it.

As I said, it revs high for a few minutes, then drops down to normal idle speed, the diesel heater is staying on for quite a long time, even if you've just stopped to fill up after a hour long drive.

I did recently have the car into a garage where they diagnosed and fixed my turbo drop out and limp issue, luckily wasn't the turbo seizing, it was the control valve, replaced been fine since.

I have noticed in the last few months, before this issue started and before the valve change, that it does blow a cloud of smoke on start up, and that occasionally it's not as keen to start as it has been and also occasionally once started for the first few seconds there is a slight unevenness in the running, was wondering if the battery or a heater was going home.

Tom

I have noticed in the last few months, before this issue started and before the valve change, that it does blow a cloud of smoke on start up, and that occasionally it's not as keen to start as it has been and also occasionally once started for the first few seconds there is a slight unevenness in the running, was wondering if the battery or a heater was going home.

Mine sometimes generates a small cloud when starting (haven;t seen it recently though), never had the rough running though.

The slowness to start could either be failing glowplugs or a dodgy battery (if when cold), or maybe a slight sticky anti-shudder valve. However do remember that failing CTSs don't also flag up faults, so it might still be a CTS issue.

Edited 8 November, 201114 yr by mbames

Mine sometimes generates a small cloud when starting (haven;t seen it recently though), never had the rough running though.

The slowness to start could either be failing glowplugs or a dodgy battery (if when cold), or maybe a slight sticky anti-shudder valve. However do remember that failing CTSs don't also flag up faults, so it might still be a CTS issue.

A failing CTS will only log a fault when it gives the ECU a reading outside the allowed range (i.e. it tries telling the ecu it is -50 outside or something else daft), if it gives the wrong reading within the right range then no fault is logged but funny things happen.

Out of interest when was the cambelt last changed? If the fuel injection pump timing is out then it will be difficult to start.

If the battery is failing I would expect it would also be difficult to start when warm, as the engine has to be doing 250rpm before the fuel is turned on.

Not sure where to go from here.

Loathe to buy a new sender if nothing wrong with the current one. I'm sure Jorily won't send me one on the off chance.

I think the battery might be beginning to fade, but it's not a worry yet. There could also be one or more heaters getting near the end of their life, but again not terminal yet.

It's the long heat and fast idle that I want to address first.

Can the sensor be checke with a meter? Does anyone have a known good one sat on a shelf that they could put a meter across and see if they get readings, then try sticking it in a mug of boiling water and see if the readings change?

Tom

You have a VAG lead, which means you can monitor the output from the CTS to the ECU.

Is its value similar to that displayed on the temp gauge or similar to ambient before the car is started?

You have a VAG lead, which means you can monitor the output from the CTS to the ECU.

Is its value similar to that displayed on the temp gauge or similar to ambient before the car is started?

OK, I have the lead, but all I have software wise is VCDS Lite, I'm guessing you need the licenced version for such fancy stuff?

Tom

VCDS Lite only allows you to view groups 001-025, but that's fine as IIRC, the value you want is at MB1.4. It may be labelled as G62.

Here is the link that shows the difference the different versions http://www.ross-tech.com/vag-com/vag-functions.html

OK, I'll check if I can read that, otherwise I think I'll need to register, looks like it might be worth while anyway.

Tom

OK, tonight there is an error code:

17664 - Engine Coolant Temp Sensor (G62): Open or Short to Plus

P1256 - 35-00 - -

Also reading MB1.4 I get -28° (it had recently been running) which as I watched with the engine running dropped to -35°.

Seems that could be slightly wrong to me?!

Tom