Sat nav-vauxhall astra

Your code 21 is just telling you that your left sidelight is out. The shaking and juddering is a different issue and needs a pro grade scan tool computer to see which sensor needs replacing.
21 Failure of left sidelight.

Vauxhall Astra Fault Codes - - Driving Test Tips

https://www.drivingtesttips.biz > fault-codes
Vauxhall Astra Fault Codes List ; 21, Failure of left sidelight. ; 22, Failure of right sidelight. ; 23, Failure of reversing light. ; 24, Failure of number plate ...

maybe this will help good luck

Some cars with an ecu have a default setting whereby they run but only at idle. Go to your local Vauxhall dealer, look sweet and ask the service people if they can offer any idea, I mean the mechanics not the counter staff who generally don't know a handbrake from a halfshaft.
Or go on line and scour the astra owners helplines to see if its a common problem.
Don't spend a penny in a garage without checking all possible areas first. Like the other answer, it may just be a cable or electrical plug come off.

sat nav,??ive driven for years without it ,open window and ask or follow a bus ,thats my favourite

the astra convertable is prone 4 this problem take it to vauxhall there is a rework and it wont cost u a penny!!

I have the manual for the MyGuide 3000GO. Send me your e-mail address so I can give it to you.

I can send you a manual for a myguide 3100 if thats any use. The 'm' should stand for menu. Date and time will update automatically as it connects to satellites

did any of you find one? i have just bought a SECOND HAND 2004 CRV but no sat nav manual - nothing on the net- any help appreciated.

please check www.playpower.com.cn

Most units are fitted behnd the glove box a couple of screws in it & under it, and the whole thing will come out.

if it has an adjustable sensor then there could be a small hole with a - + a small screw driver turns it up or down, it could well be one that needs programing via software inother words there is a set up sequence which puts the alarm in programing mode...

It depends on the manufacturer. (WHAT ALARM IS IT?)