C5 speedo

robba · Post by **robba** » 04 Aug 2005, 15:20

My C5 hdi speedo reads around 30% below the cars actual speed!
Whats the problem,speedo head,sensor,transducer??
Has anyone seen this problem,Citroen Australia appear confused.They want to replace everything and charge a fortune!

jeremy · Post by **jeremy** » 04 Aug 2005, 15:47

had this on an XJ6 many years ago - indicating 70 - then looked at the rev counter - 4500 rpm - 117 MPH - oops - Thats why it wouldn't accelerate rapidly!
Jeremy

Kowalski · Post by **Kowalski** » 04 Aug 2005, 17:12

I wonder whether an intermittent connection somewhere on the wiring could cause it. If it is just dirty connectors, just unplugging, drying and spraying them all with silicone oil before putting them back together should sort it out.

aengus · Post by **aengus** » 04 Aug 2005, 17:23

my XM V6 speedo currently over-reads by around 22% compared to GPS. Strangely, rev's appear to read correct for displayed speed on the speedo, which makes me wonder about the box/final drive rather than the speedo pickup - tried several different speedo's from other V6's with same result.
Dave

Mosser · Post by **Mosser** » 04 Aug 2005, 17:43

The Seat Leon has a speedo that over reads by 9% on pretty much all of the range, but interestingly, if you bring up the diagnostics menu in the climate control system, you can access and view the actual speed of the car, it seems that Seat decided that the speedo needs to over read on the speedo, even though the ECU knows the exact speed the car is doing, i compared it to my sat nav system and the climate control speedo was within 1% of accurate, the speedo was always 8-9% out,
I think it has to do with the law which states that speedo's are allowed to over read by 10% but under read by 0%, so they add in some over reading to be within the law

406 V6 · Post by **406 V6** » 04 Aug 2005, 17:45

It appears to be a problem of the instrument cluster, translating incorrectly the information given by the sensors.