Citroen C5 - Speedometer accuracy

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Sun 20 Jan 2013 11:01
Citroen C5 - Speedometer accuracy - chalfont

My car was registered in 2006.

Having been stopped by the police several times and informed I had been exceeding the posted limit and told that my speedometer ought to be tested and recalibrated I wonder what my options are.

I used my TomTom GPS device and discovered that the speedometer consistently showed 7mph less than the GPS.

My local Citroen dealer cannot help with recalibration.

Should Citroen as a manufacturer be liable for any modifications>

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Sun 20 Jan 2013 11:35
Citroen C5 - Speedometer accuracy - Collos25

Its either got wrong size tyres or the algorithm in the ECU is not correct.

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Sun 20 Jan 2013 13:01
Citroen C5 - Speedometer accuracy - jc2

7 mph at all speeds???

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Sun 20 Jan 2013 13:43
Citroen C5 - Speedometer accuracy - Cyd

If you are cruising at a steady 70mph on a motorway and the TT has connection to at least 5 satelites (highly likely) thn it should be accurate to +/-1mph. If under these conditions your speedo is showing c63mph, then that is illegal !!

It is astounding that your local dealer says they cannot help. Most cars can have the tyre diameter reprogrammed via the OBDII port. Insist that they contact Citroen for the necessary help and advice, or do so yourself. In the first instance, they should be able to tell you what the correct tyre size is for your car. Assuming you have the correct tyres, then th eelectronics will need reprogramming.

You could try putting your registration into the Blackcircles tyre chooser and see what size it gives for your car. Does this match what's fitted? Not 100% conclusive, but a good indicator.

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Sun 20 Jan 2013 14:07
Citroen C5 - Speedometer accuracy - Galaxy

Either wrong sized tyres and/or wheels are fitted or there's an ECU programing problem.

Just use the satnav as a solution? Speedometer calibration isn't checked during the MOT test, it just has to be working!

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Sun 20 Jan 2013 17:44
Citroen C5 - Speedometer accuracy - rebel

"Speedometer calibration isn't checked during the MOT test, it just has to be working!"

Wrong - Speedo is not a testable item in the MOT test.

It cannot be failed for function, accuracy or even existence.

Construction and use regulations are another matter though

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Sun 20 Jan 2013 18:48
Citroen C5 - Speedometer accuracy - Galaxy

Wrong - Speedo is not a testable item in the MOT test.

It cannot be failed for function, accuracy or even existence.

Construction and use regulations are another matter though

mottesters.co.uk/files/special%20notices/MOT%20Ins...f

Sorry, but it's not wrong. Please see link above, Section 6.7, Page 152.

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Sun 20 Jan 2013 20:27
Citroen C5 - Speedometer accuracy - rebel

Sorry Galaxy, I stand partially corrected.

Thats a very recent addition to the MOT test.

It now has to be present and must illuminate.

But there is still no check for it's functionality or accuracy.

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Sat 16 Feb 2013 17:40
Citroen C5 - Speedometer accuracy - chalfont

Thank you, a couple of good suggestions there.

I will write to Citroen UK, who incidentally just passed the buck back to my local dealer, and insist they make the dealer aware of the tyre diameter calibration.

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Sat 23 Feb 2013 17:32
Citroen C5 - Speedometer accuracy - Andrew-T

I will write to Citroen UK, who incidentally just passed the buck back to my local dealer, and insist they make the dealer aware of the tyre diameter calibration.

You must have put on some pretty big wheels to make (more than) 10% difference to your apparent speed. Is the display digital or a 'traditional' meter? Surely the problem is in the calibration somewhere?

Edited by Andrew-T on 23/02/2013 at 17:34

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