Gearbox occasionally doesn't go into 5th

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stevesey

MB Enthusiast
Joined
Sep 3, 2007
Messages
2,969
Location
Bristol
Car
Alfa 156 1.8TS
Noticed that in very specific circumstances the gearbox doesn't go into 5th (temporarily)

Has Happened 3 time this year now - all after stopping for between 5-10 minutes and then pulling away and after a couple of junctions accelerating moderately briskly up to 70mph. Obvious example is a splash and dash at the motorway services - that time I pulled over to the hard shoulder stopped and re-started and all ways fine. The other two times was on a ring road and it cured itself after slowing for the next roundabout and pulling away again.

Dipped the box when I got home tonight and the level is spot on.

Any ideas?

Other than an occasional slight flare from 3rd to 4th - again when conditions are just right - all is fine with the box (153K miles old now).
 
I have exactly the same problem. It's okay at the moment but on a few journeys I had to "tip" in 5th and it would drop back down to 4th at the slightest encouragement.



A Star readout gives the following.

P2602: The voltage supply of the valves is faulty.
P2502: The gear is implausible or the transmission is slipping.

My mileage is 143,000 and I have been planning an ATF change for a while now.


Enter Olly or another genius..
 
Perhaps you should change the fuel filter as if its old it might hold the power therefore the gear will not switch up.
For less then a tenner I'll strt there :)
Olivier
Oh, make sure the pre-filter is clean too.
 
IA Star readout gives the following.

P2602: The voltage supply of the valves is faulty.
P2502: The gear is implausible or the transmission is slipping.

My mileage is 143,000 and I have been planning an ATF change for a while now.


Enter Olly or another genius..
Hm - a sensor/electro plate issue perhaps.

Was thinking about asking Olly to put mine on Star on the 15th to see what it says.
 
This looks like a possible speed sensor issue. A Star will tell all.
 

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