Hi Guys. 

Please forgive me for posting a  VW problem on the forum. I'm still the owner of a Octavia and have had several problems fixed by you guys on Briskoda. Hopefully the electrics will be similar.

Problem: 2015 Passat reading 10 -12 degrees low. I was told to change sensor which is situated in grill behind the front number plate area. Fitted the new sensor tonight and exactly the same temp reading ! any ideas?

Regards

I 

Firstly, do you see any error codes if you scan with VCDS or an OBD reader?

The ambient temperature would not really cause any real problems if its not working so it is normal for it to be substituted when one of the other intake air températures if it is missing/in error.

Perhaps you are really reading the turbo charger inlet temperature as a substitute for the sensor which has an electrical error/broken wire/etc.

 

If there are no errors indicated for the ambient temperature sensor I would look at:

- bad wiring connection (increasing the resistance measured by the ECU - try checking the sensor connector for signs of wear or corrosion - same on the ECU side.

- ecu error - dry solder joint or similar causing a problem. (obviously much harder to diagnose & test/replace)

Edited 9 January, 20197 yr by Gabbo

Could have been a wiring fault in the first place - it's rather prone to the elements.

 

I think there is possibly a second Outside Air Temp sensor in the plenum - didn't think it was for use with the temp display but worth a look [EDIT possibly not on your model - just remember another sensor relating to aircon in some way]

 

 

Edited 9 January, 20197 yr by bigjohn

Thanks guys. I remembered I had taken extended warranty out on the car which runs out in April so have booked it in to the local VAG dealer on Tuesday but I will check the connections again. Will get back on the outcome. 

Regards 

Hi guys, question for Octavia outside temperature reads.

I have it parked all day in an underground parking lot, where there are around 10 degrees celsius. 

When leaving from work, outside ar -7 degrees, but it take the car around 15 minute to read this temp. Is this normal? Shouldn't be quicker? It goes down from 12.11..10...0., -1, and so on. I park at home after 15-20 min, and I am still not sure it reached to correct value

Hi Guys

This morning the temp is reading correctly and has continued to do so throughout the day. Could this be down to it resetting itself with the new temp sensor fitted? Perhaps I didn't switch the ignition off for long enough me thinks. Anyway it’s working ok. Will go out and check it later on. Hopefully can cancel having to take it into the dealer. They were going to charge £72 for the diagnostics.

 

Regards

On 09/01/2019 at 12:12, Gabbo said:

The ambient temperature would not really cause any real problems if its not working

Well, unless you have Climatronic, which uses this to determine how much to heat cabin air by to achieve the demand temperature, or it gets used by cold enrichment on that engine.

Hi Ken

The car does not have climatronic  and the false ambient temperature reading was not affecting the running. Just fed up with danger of ice coming up every time I started car, even though it was 12c. Anyway fingers crossed its fixed now.

 

Regards

The ambient temperature is normal not very accurate due to issues with sensor placement (heating from the sun in the Mirror or heating from the engine if placed around the bumper).

For the engine, there is usualy an intake air temperature sensor which is used for the important calculations along with the Boost Air Temperature &/or intercooler temperature.

I'd imagine a climatronic system would also have an internal temperture sensor before heater matrix to aid the control of the mixing but I'm not too familiar with these system.

Hi 

Attached is a pic of the offending sensor. Now the outside temperature on the Passat reads the same as the Octavia parked along side it. That's the problem fixed. Don't understand why explanations of temperature calculations for boost/ intercooler etc are relevant for the posting. Thanks all the same. 

 

Regards 

 

 

2 hours ago, benterrier said:

Hi 

Attached is a pic of the offending sensor. Now the outside temperature on the Passat reads the same as the Octavia parked along side it. That's the problem fixed. Don't understand why explanations of temperature calculations for boost/ intercooler etc are relevant for the posting. Thanks all the same. 

 

Regards 

 

 

 

22 hours ago, KenONeill said:

Well, unless you have Climatronic, which uses this to determine how much to heat cabin air by to achieve the demand temperature, or it gets used by cold enrichment on that engine.

Which part of that is confusing you? Accepted you don't have Climatronic, but I didn't have that information yesterday.

So I am having the same issue. Replaced the ambient air temp sensor and the cabin read out on dash fluctuates badly meaning no A/C and I'm in an Australian summer!

 

I see that potentially this sensor may be at fault. Where exactly is this sensor located?

On the Passat it was down by the front number plate behind bumper area, it didn't take much locating when you're down there.

Ok. So is this an additional temp sensor to the other one behind the grill? Or do you only have the one sensor behind the grill?

 

any updates? we have a B8 passat 1.6 diesel with same issue ( shows 10 degrees less than actual temperature ) 

Don't know if this is of any help?