Automatic kicking out of 4th gear into 3rd

Hello there,

I am posting on behalf of my mother who is having issues with her automatic Citroen C3. The car has started dropping out of 4th gear (making a loud noise) and going into 3rd. If she turns the car off then back on, it will return into 4th but the problem might return.

She has a C3 1.6 VTi 16V Exclusive 5dr Auto. Car is a 2010.

She has taken it to the usual mechanical who hasn't been too forthcoming - says it might need a software update or something as the fault code is too generic. I'm not sure.

Any advice?

Thanks in advance.

sprst wrote: ↑Sun Feb 09, 2020 6:35 pm Hello there,

I am posting on behalf of my mother who is having issues with her automatic Citroen C3. The car has started dropping out of 4th gear (making a loud noise) and going into 3rd. If she turns the car off then back on, it will return into 4th but the problem might return.

She has a C3 1.6 VTi 16V Exclusive 5dr Auto. Car is a 2010.

She has taken it to the usual mechanical who hasn't been too forthcoming - says it might need a software update or something as the fault code is too generic. I'm not sure.

Any advice?

Thanks in advance.

Hi

This isn't a job for your usual mechanic if they are not fully aware of the AL4 auto box. A specialist in automatics will be a better choice because that AL4 is used across several marques and many models. They would have seen the '4th to 3rd with a jolt' before.

The problem can usually be cured with draining and refilling the AFT fluid (special LT71141 AL4 stuff here) but if the problem has been left too long it may need a autobox overhaul.

Arfur Dent wrote: ↑Sun Feb 09, 2020 7:20 pm

sprst wrote: ↑Sun Feb 09, 2020 6:35 pm Hello there,

I am posting on behalf of my mother who is having issues with her automatic Citroen C3. The car has started dropping out of 4th gear (making a loud noise) and going into 3rd. If she turns the car off then back on, it will return into 4th but the problem might return.

She has a C3 1.6 VTi 16V Exclusive 5dr Auto. Car is a 2010.

She has taken it to the usual mechanical who hasn't been too forthcoming - says it might need a software update or something as the fault code is too generic. I'm not sure.

Any advice?

Thanks in advance.

Hi

This isn't a job for your usual mechanic if they are not fully aware of the AL4 auto box. A specialist in automatics will be a better choice because that AL4 is used across several marques and many models. They would have seen the '4th to 3rd with a jolt' before.

The problem can usually be cured with draining and refilling the AFT fluid (special LT71141 AL4 stuff here) but if the problem has been left too long it may need a autobox overhaul.

Thank you for your timely advice. Do you know how many litres of this fluid are needed?

And this is likely to just completely fix the problem?

Thanks!

Arfur Dent wrote: ↑Sun Feb 09, 2020 7:20 pm

sprst wrote: ↑Sun Feb 09, 2020 6:35 pm Hello there,

I am posting on behalf of my mother who is having issues with her automatic Citroen C3. The car has started dropping out of 4th gear (making a loud noise) and going into 3rd. If she turns the car off then back on, it will return into 4th but the problem might return.

She has a C3 1.6 VTi 16V Exclusive 5dr Auto. Car is a 2010.

She has taken it to the usual mechanical who hasn't been too forthcoming - says it might need a software update or something as the fault code is too generic. I'm not sure.

Any advice?

Thanks in advance.

Hi

This isn't a job for your usual mechanic if they are not fully aware of the AL4 auto box. A specialist in automatics will be a better choice because that AL4 is used across several marques and many models. They would have seen the '4th to 3rd with a jolt' before.

The problem can usually be cured with draining and refilling the AFT fluid (special LT71141 AL4 stuff here) but if the problem has been left too long it may need a autobox overhaul.

Passing on your information to my mother, she has revealed that her mechanic spoke to someone Citroen and they said the fluid change would be unlikely as the car has only done 24,000... but it is 10 years old. What do you think?

AL4 takes 4.5L.

There is a procedure to refilling, needs access to lexia and I suggested an auto gearbox specialist to diagnose because they would understand the dropping into 3rd better than a mechanic who may not deal with autos very often.

Having those miles over those years in not usual, so the usual probably won't apply.

The classic failure mode for the AL4 gearbox is sudden (and typically violent) changing of gears up or down to 3rd, depending what gear you were in and how fast you were going at the time. This is accompanied by three beeps with the star and S symbols flashing on the dash. This means that the gearbox ECU (electronic control unit) has detected a situation that the ECU can not deal with and goes into "fail safe mode" (locked into 3rd gear). Typically if it's a transient failure, stopping, turning off the ignition then restarting the car will "clear" the fault and the car will run normally (for an indeterminate period of time).
Now there are a lot of things that can go wrong with an auto gearbox and I will say straight up... I can not tell you what is wrong with your mothers car!
However there a few "usual suspects" that tend cause problems.
Bad oil. If some people on the internet are to believed, not using Esso/Mobil LT71141 based transmission fluid will cause your gearbox to blow up and Donald Trump to gain another 4 years in the White house!!! But seriously...a low grade or cheap oil may not have the properties required for the gearbox to function correctly and when it wears out may cause the transmission to fail. If the transmission oil has NEVER been changed, Citroen says its good for life. Yep, if the oil has never been changed it's unlikely to be the problem. I have seen 1 or 2 posts saying changing the oil fixed problems but they seem to be the minority.
Gearbox update. If the transmission ran fine for 10 years why didn't it need an update before now? If there were problems with the software it would have turned up way before this. Besides to my knowledge there have been very few updates since 2003!! The transmission is a relatively old design.
The modulator valves. In the transmission there are two valves that are used to regulate hydraulic pressure. They each are about the size of a stack of ten 20p coins. One or more of these valves can stop working correctly. This tends to be the major cause of failure of the gearbox.
Have a look in my topic "replacing modulator valves in an AL4" in the auto gearbox section just below your (this) topic. Follow the links to see how the valves are actually replaced.

If you have no intention of doing the work by yourself, I would suggest you find a specialty auto gearbox vendor and ask them if they have experience with AL4 or DPO (dee-pee-oh) transmissions. If they don't...move on to someone who does.