Any car mechanics here? (aka My OH's car has developed a sense of humour...)

[SatNavSaysStraightOn]

Quick question for you if you are a car mechanic.

The external temperature reading is becoming somewhat 'variable'. Today whilst driving it, inside 120 seconds, I saw it plummet from recording a balmy +10C outside to -21.5C! I don't think the weather got that cold...

Should we be concerned about this? Will it have an effect on things like fuel economy? One noticeable effect has been the internal heating (and I hate hot air being thrown at me) ... It's a 2002 VW Passat.

I got a photo it, because as with all 'random' faults I doubt it will actually play up if we take it to the garage...

 

[oldfatfool]

Surprised it as effected the internal heating tbh as this is controlled by an internal sensor whilst afaik the external temp is taken from a sensor behind the bumper, by the same token I wouldn't have thought that it would effect fuel economy as the oil temp and water temp will be the parrameters used by the ECU along with info from the MAF etc,
Is the car erratic or revving higher than usual at tick-over when warmed up, as this would be an indicator that it could be causing an issue??

As the car had a bump at all that might have damaged the sensor??

Not a mechanic btw just my thoughts.

 

[fossyant]

How long has it done it for. If it's a one off, just ignore it as you may have driven past a ghost (heh heh).

Regular, then I'd personally try a reset, i.e. Disconnect the battery for 20 minutes.

My car has on occasion thrown up silly messages. The dash once failed to work, but I knew the fix was a 20 minute disconnect en the fuel and speed worked again as it's all electronic (on a 2002 Nissan Primera).

The other option is check out a Passat forum. I am a paid up member of a particular Nissan forum as it has saved me a fortune as the car has all sorts of hidden ways of resetting and checking the electronics without a computer.

 

[MarkF]

Take the fuse out, if the fuse controls several things then just remove the relevant bulb. Not a mechanic, just what I usually do..................

 

[shouldbeinbed]

How long has it done it for. If it's a one off, just ignore it as you may have driven past a ghost (heh heh).

Regular, then I'd personally try a reset, i.e. Disconnect the battery for 20 minutes.

My car has on occasion thrown up silly messages. The dash once failed to work, but I knew the fix was a 20 minute disconnect en the fuel and speed worked again as it's all electronic (on a 2002 Nissan Primera).

The other option is check out a Passat forum. I am a paid up member of a particular Nissan forum as it has saved me a fortune as the car has all sorts of hidden ways of resetting and checking the electronics without a computer.

Which Nissan forum? our Qashqai is heading towards middle age & we're not in the market to replace it for a while yet.

sorry. SNSSO can't add anything more other than our Passat had spates of stupid hiccups like this and bits falling off every 3 years or so.

 

[fossyant]

Which Nissan forum? our Qashqai is heading towards middle age & we're not in the market to replace it for a while yet.

sorry. SNSSO can't add anything more other than our Passat had spates of stupid hiccups like this and bits falling off every 3 years or so.

NPOC. Been there longer than in here. Had my P12 Primera for 11 years as the car is just 12 years old now (one of the first UK cars). Most of the shortcuts work for most models believe it or not. The P12 was very advanced at the time, and I bet most of the 'resets' work in the Quashi. I can still get the satnav updates off ebay for less than a tenner.

 

[fossyant]

Oh and the biggest rip off is the recoding of the remote switches for the central locking. The car will do upto 4 fobs itself. In the newer models, the fob is part of the key, but the same applies. You can't recode the NATS in the key blade part.

 

[SatNavSaysStraightOn]

Which Nissan forum? our Qashqai is heading towards middle age & we're not in the market to replace it for a while yet.

sorry. SNSSO can't add anything more other than our Passat had spates of stupid hiccups like this and bits falling off every 3 years or so.

yep - beginning to feel that way about ours as well. last issue was it locking us out on the rear passenger door which locked and would not unlock at all from the inside or the outside - could not open the door at all. After 4 months like this (and refusing to take passengers on that side) we had the garage look at it. electric wires replaced got it working for a day then it gave up again and they ended up drilling the lock out and replacing it - that has cured the problem. Now the rear drivers door is showing the same symptoms, so it is in on Thursday to have the lock replaced before it gets to the point of needing to be drilled out! The boot did something similar (solenoid issue that time) which failed in the open (not even unlocked!) position and I repaired that one myself... solenoids I can do, but dismantling the trim, and resorting to drilling locks out is not something I want to do!

@oldfatfool
We don't have the radio code so disconnecting the battery is not an option, but no the car has not had a bump (at least not past the towbar finding a wall at less than 1mph (in reverse) and it being an automatic it stops of its own accord (low wall my OH did not see!)) no other erractic issues, but we have had a timing belt bolt shear off of its own accord! Even the garage could not work that one out and had not come across that issue before.

As for the temperature gauge, I figured it should be only display, but it definitely started throwing hot air at me to warm up the interior of the car, but I guess if it thinks the external temp has dropped by 30 degrees, it thinks the passengers will be cold!

 

[marknotgeorge]

The external temp sensor is usually behind the front bumper somewhere, and doesn't usually affect the climate control. It certainly won't affect the engine, which will have it's own sensor. I don't think the sensors themselves are that expensive (£20-30), the problems come if it's the wiring.

 

[oldfatfool]

@oldfatfool
We don't have the radio code so disconnecting the battery is not an option,

I would check with the garage, I know new cars the stereo is coded to the car rather than having a code to enter if the battery is removed, not sure on a 2002 though.

edit, older VAG radio codes have been known to be on the tag that comes with the second key, stuck in the front page of the handbook along with all the spec codes for the car and also on a sticker under the ashtray. Worth a look.

 

[stephec]

Similar thing happened to a Mazda6 I had about ten years ago.

External temperature wrong would make the climate control blow wrong inside the car to compensate for what it thought was outside.

It was a faulty external temperature sensor in the end.

 

[fossyant]

sorry. SNSSO can't add anything more other than our Passat had spates of stupid hiccups like this and bits falling off every 3 years or so.

Hasn't happened with my P12. So far in over 11 years of owning the car have I only had two big bills, £400 ish for new air con rad that had a hole from a rock impact, and £600 for a new cat. Tyres as and when, new ABS ring/front hub (less than £200 fitted), servicing by me, the odd part from ebay (new heated mirror glass for £12). Anti roll bar links done recently as they rattled, but getting over 80k out of them is blooming good - cheap too, but garage fit as seized on from new. Car is now on 94k and I bought it with 10k on the clock. NO rust, other than some on the front radiator support that's norm with Nissans as they don't protect them (lazy buggers) - so it's greased internally and painted by me.

It just does not like being sat on the drive most of the winter for short trips. OK in summer as we take the bikes down to North Wales most weekends. Running like new at the minute and clocked up just over 42 mpg on a 65 mile run to Wales recently, best I've had. It's petrol !! Down to low 30's with the 4 bikes on the roof, as it totally hammers the aerodynamics. Need a few Venge's up there.

 

[fossyant]

Radio's are hard coded to the car, so a battery reset won't affect it. Just check a Passat forum. Moving radio's between cars is tricky - it's a dealer job.

 

[fossyant]

The car may have a more basic air con - mine has "climate", so a temp sensor inside and out, as well as a solar glare/gain one (yup 12 year old car).

Worth a gander with the forum experts. You know what we are like with bikes, the car lot know their stuff too.

 

[SatNavSaysStraightOn]

The car may have a more basic air con - mine has "climate", so a temp sensor inside and out, as well as a solar glare/gain one (yup 12 year old car).

Worth a gander with the forum experts. You know what we are like with bikes, the car lot know their stuff too.

It has climate control as well... think we are still picking up the 'faults' from having purchased it last year still I guess once we iron out the faults it should be OK even if it sounds like a tank...(diesel 1.9 tdi 5 speed auto in the higher bhp version). have spent very little on it since it was purchased so that's one bonus.