Audi speedometer under reads by 25mph so failed MOT.

[rod_vw]

So if it was your car John would you reject the MOT?

I thought the brake test was driving the car around the block with an inertia gauge in the passenger footwell.

Yep, a Tapley Meter is still a valid method of testing braking systems in certain circumstances.

 

[L' Hobo]

I know it's O/T but there are some knowledgeable folk on Fun so worth asking.

2004 Audi TT 3.2L Roadster.
It's my son's treasured car and has just failed the MOT as the speedo needle at rest is below the 0 mph position and therefore reads a constant 25mph slower than the road speed. It's as though the needle has slipped round on its spindle. All other dash dials and lights are working fine.
The local MOT garage can't (doesn't want to) deal with it and the Audi main dealer said they would have to sub it out to a specialist but wouldn't suggest who it was.
I've Googled and YouTubed the symptoms til I'm blue in the face so have a fair idea of the workings and potential causes but have decided we need to take it to a specialist since although I'm experienced in vehicle mechanical work and straightforward electrics I've seen on YouTube that the stuff behind the dash cluster and dials is all delicate pcbs and chips. I'm near Brighton and have found on Google a specialist in dashboard cluster repairs ('from £150') near Portsmouth, about 60 miles from me but can anyone suggest someone nearer?

When I was in the transport game, speedo's were not part of the MOT and you could not fail a vehicle unless it was not illuminated.
I would challenge!
I still have a testers manual, if I remember, I will check tomorrow.

 

[Landy Andy]

Yep, a Tapley Meter is still a valid method of testing braking systems in certain circumstances.

Yes. Thats how they still test mine.

 

[L' Hobo]

Yep, a Tapley Meter is still a valid method of testing braking systems in certain circumstances.

but that's testing the brakes, not the speedo? I would use another garage with a 'rolling road' if that was the only thing it failed on as using a sat-nav today gives a more accurate speed reading.

 

[Landy Andy]

but that's testing the brakes, not the speedo?

The point is against this comment

“The tester has no authority to drive the car during the test and whatever the result was it can't be applied to the test”

^{_{Subscribers  do not see these advertisements}}

 

[L' Hobo]

The point is against this comment

“The tester has no authority to drive the car during the test and whatever the result was it can't be applied to the test”

Sorry! I thought the OP's original question was about the speedo?

 

[62272]

(below is what the gov website says on the subject​

7.8. Speedometer, Hidethis section​

You must check the speedometer of vehicles first used on or after 1 October 1937 with a maximum speed above 25mph. You do not need to check Class 3 vehicles.
If a road test is needed, for example to carry out a decelerometer test, you must check whilst driving that the speedometer is working.
If a road test is not necessary, you should only reject a speedometer if it’s clearly not working.
Speedometers do not need to be lit on:

• vehicles with no front or rear position lamps
• vehicles that have front or rear positions lamps that are permanently disconnected, painted over or masked

You can accept a tachograph as an alternative to a speedometer if it satisfies the requirements of this inspection.

Defect	Category
(a) Speedometer not fitted where one is required	Major
(b) Speedometer: (i) operation impaired (ii) not working	Minor Major
(c) Speedometer: (i) not sufficiently illuminated (ii) not illuminated

 

[L' Hobo]

(below is what the gov website says on the subject​

7.8. Speedometer, Hidethis section​

You must check the speedometer of vehicles first used on or after 1 October 1937 with a maximum speed above 25mph. You do not need to check Class 3 vehicles.
If a road test is needed, for example to carry out a decelerometer test, you must check whilst driving that the speedometer is working.
If a road test is not necessary, you should only reject a speedometer if it’s clearly not working.
Speedometers do not need to be lit on:

• vehicles with no front or rear position lamps
• vehicles that have front or rear positions lamps that are permanently disconnected, painted over or masked

You can accept a tachograph as an alternative to a speedometer if it satisfies the requirements of this inspection.

Defect	Category
(a) Speedometer not fitted where one is required	Major
(b) Speedometer: (i) operation impaired (ii) not working	Minor Major
(c) Speedometer: (i) not sufficiently illuminated (ii) not illuminated

While I do not wish to be argumentative, can I ask what Government website you retrieved that from?

The reason I ask is that I have braved the pouring rain (brave little soldier ) to get my 1997 PSV MOT manual issued by the
Public Vehicle Inspectorate which we used when visiting the Government Testing Station at Guildford.

On page 26, it clearly states that under,
Procedures and Standards

* Check that a tachograph or speedo is fitted and is complete.

* Check the condition and that it can be illuminated.

Note: If the dial glass is cracked and this does not affect operation this is not a Reason for Failure but the presenter should be advised of the defect.
---------------------------------------------------------------------------------------------------------------------------------------------------

My argument would be that it should be an 'Advisory' not a 'Fail' as the son's speedo was complete (just the arm slipping) and could be illuminated but could not be tested for accurately if it had been brake tested on a rolling road and, without the help of a SatNav (or similar) how could a mechanic test it for accuracy on the public road?
If the mechanic had that help from the owners SatNav, then so would the owner! (I rest my case your honour!)

 

[62272]

While I do not wish to be argumentative, can I ask what Government website you retrieved that from?

The reason I ask is that I have braved the pouring rain (brave little soldier ) to get my 1997 PSV MOT manual issued by the
Public Vehicle Inspectorate which we used when visiting the Government Testing Station at Guildford.

On page 26, it clearly states that under,
Procedures and Standards

* Check that a tachograph or speedo is fitted and is complete.

* Check the condition and that it can be illuminated.

Note: If the dial glass is cracked and this does not affect operation this is not a Reason for Failure but the presenter should be advised of the defect.
---------------------------------------------------------------------------------------------------------------------------------------------------

My argument would be that it should be an 'Advisory' not a 'Fail' as the son's speedo was complete (just the arm slipping) and could be illuminated but could not be tested for accurately if it had been brake tested on a rolling road and, without the help of a SatNav (or similar) how could a mechanic test it for accuracy on the public road?
If the mechanic had that help from the owners SatNav, then so would the owner! (I rest my case your honour!)

MOT inspection manual: cars and passenger vehicles - 7. Other equipment - Guidance - GOV.UK

Seat belts and restraint systems, airbags, anti-theft devices, horn, speedometer, speed limiter and electronic stability control (ESC) rules and inspection for car and passenger vehicle MOT tests.

www.gov.uk

(apologies for the delay, I was out earlier )

 

[L' Hobo]

MOT inspection manual: cars and passenger vehicles - 7. Other equipment - Guidance - GOV.UK

Seat belts and restraint systems, airbags, anti-theft devices, horn, speedometer, speed limiter and electronic stability control (ESC) rules and inspection for car and passenger vehicle MOT tests.

www.gov.uk

(apologies for the delay, I was out earlier )

Thankyou! Your version is certainly more up to date than mine but as the Speedo is still working (just running 25mph slower) I would still argue to the MOT station that it is 'impaired', not broken!

This 'impairment' is classed as a 'minor' defect which is not a failure but an Advisory.

(I would still, next time, take it to a garage with a 'rolling road' )

^{_{Subscribers  do not see these advertisements}}