Vauxhall Zafira 2002 elegance automatic transmission problem

GalacticaActual

Hello everyone.

So , the Mrs Zafira is playing up again.

Its an automatic transmission , and every so often seems to get stuck at 40MPH.  Sometimes 3 or 4 times in the space of the journey, sometimes just once while out.
Revs dont go up or down and power seems to drop. Then if you take your foot of the throttle pedal and then put it back down , the car seem to drop a gear and get going again. We have taken it to a garage and typically , when they took it for a test drive , it didn't happen.

Does anyone have any ideas what it could be please?

Thanks.

car-man

First of all do the brake pedal test to check for fault codes....

Ignition off, press accelerator and brake pedal together then turn on the ignition without starting the engine and watch the speedo mileage window for fault codes to show up, if there are codes it will display them with ECN above....when a row of zero appears the code reading has finished...if zero appears instead of codes then there are no codes to display.
Look up any codes found on the internet.

When I've had mystery problems with conventional auto gearboxes they are usually fixed by changing the gearbox oil and the internal filter.

GalacticaActual

Thanks.

With the break pedal test, where exactly are the codes shown  ?
On the speedometer it's self  ?

The dot matrix display on the dash where the clock ect is  is knackered and didn't show anything....

car-man

Codes are shown where the mileage is displayed, on the speedometer, yes.

GalacticaActual

Thanks.

That display is also broken   

Think the car has got to go.

It's not just at 40mph either  It's at all different speed.

IronGiant

If they can't read the mileage, would that fail an MOT?

car-man

Not a failure, they just record it on the certificate as "mileage not displayed."

GalacticaActual

Garage looked at it today

They say code on the ecu is saying an airflow sensor

They can't promise this would fix the problem.

Is it a likely cause if the problem?

GalacticaActual

Oh and apparently it can happen at any speed  and not all the time  

In fact every time its been looked at it hasn't done it....

IronGiant

I suppose a sudden loss of power could cause your gear box to inexplicably change down when reapplying the accelerator.   Getting the air flow sensor sorted will certainly be a lot cheaper than the gear box