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Speed limiter switches itself off or jumps to 18 mph
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sotweedfactor   
Fri Aug 28 2020, 01:24pm
Joined: May 30 2015
Member No: #2185
Location: Surrey
 I use the speed limiter a lot and love its functionality. Apart from the common problem of the buttons not working at all (needs steering column jiggled in/out - see multiple other threads) my 2.2 seems to be developing a new aberration.

Back in the dark of winter, I was cruising along a stretch of road at 40mph with the limiter on. All of a sudden the car lost power and thankfully I managed to find a layby to roll into. After a bit of ignition on/off, I got the car started and it was OK. But I have the memory of the speed limiter display showing '18mph' at some point in this process.

A couple of days back something similar happened. I was on speed limiter at 30 mph when the display suddenly went to '---'. When I repeatedly toggled the control back through speedLimiter/cruiseControl, the speed limiter display would show firstly '18mph' and then after a second go to '---'.

A warm reboot (ignition off/on) dispelled the problem. I wonder if anyone else has encountered this exquisite little inconvenience?
Hattershaun   
Fri Aug 28 2020, 02:23pm
Joined: Dec 19 2010
Member No: #320
Location: Bedfordshire, UK
 I encountered this on a C6 2.2 auto.
There are several faults recognised by the engine ECU that de-activate the cruise control & speed limiter & stop them working (plus other things, like stopping a DPF regen).

The fault turned out to be a faulty turbo solenoid control valve, relatively inexpensive to fix.
Suggest you start with a diagnostic session to see if any fault codes are stored.
sotweedfactor   
Sat Jan 29 2022, 06:23pm
Joined: May 30 2015
Member No: #2185
Location: Surrey
 This fault has re-occurred from time to time. Over the past few months it got worse and the engine has sometimes died entirely. (Inconvenient, when cruising at 70mph along the M3!). A series of DiagBox sessions kinda indicated that this may be associated with the fault 'P0336 Engine speed signal'. A couple of weeks back, I replaced the crankshaft speed sensor (n.b. this is a 2.2HDi and the OEM part no is 1920.EH; the Bosch part number is 0986280419). I have since had no recurrence of the problem. If I do, further posts will follow!...
kitch   
Fri Mar 04 2022, 06:39pm
Joined: Sep 19 2020
Member No: #4485
Location: Hampshire
 Mine defaulted to 18mph last night, immediately after showing a 'gearbox fault' message (I know what that fault is).
Maybe it's something triggered by going into limp mode?
sotweedfactor   
Mon Mar 07 2022, 01:34pm
Joined: May 30 2015
Member No: #2185
Location: Surrey
 Hi Kitch. What was the 'gearbox fault' message, exactly? And what was the nature of the fault? Is yours a 2.2 manual? Note that 18mph = 30kph - a nice, round, default fallback sort of number. Thanks, Eric
kitch   
Mon Mar 07 2022, 04:35pm
Joined: Sep 19 2020
Member No: #4485
Location: Hampshire
sotweedfactor wrote ...

Hi Kitch. What was the 'gearbox fault' message, exactly? And what was the nature of the fault? Is yours a 2.2 manual? Note that 18mph = 30kph - a nice, round, default fallback sort of number. Thanks, Eric


The valve block is knackered (2.7 Exclusive) and when the fluid gets hot it gets a bit of a shitty on between 2nd and 3rd (eventually it just gets jammed in 3rd). Got so bad it tripped the EML (hence the warning message) and went into limp mode.

Now I think about it, you're right - it's obviously defaulting to 30km/h.
 

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