Xantia V6 with ZF HP20 in "limp mode"

[Christian S]

Hello!

I'm looking at a Xantia V6 -99 with the automatic gear box in "safe mode/limp mode". It has been for sale for a while. First it was for sale for approx £870 and now £650.

Is it possible at all to drive the car in limp mode? I've read somewhere one can pull the fuse and in that way gear up and down manually. Is that true? Is it enough to change all oil in the gear box or do I have to change the entire gear box?

[BenC5HDi]

I'm not sure of the answer to your question but without a working gearbox, the car is worth £300 max, however nice it is.

Sent from my SM-N9005 using Tapatalk

[spider]

I'd be tempted if you can to have the codes read to see what is causing it.

In theory disconnecting the battery for a short time, then re-conecting it may clear them. They will come back (possibly immediately) if serious.

It might not be *that* bad it could be a duff electro/solenoid valve or two. I'm not sure if these ones were 'updated' or not, there is some debate in my head about a dealer software update being needed to use the 'newer' designed ones (all that you can get) , although how driveable it would be until that time I'm not sure.

How bad is the limp mode ? I'd expect 3rd and reverse to work in most cases. The other 'failure' can be very nasty changes (jumping) , I've had a car (non PSA) that locked into limp mode (3rd/Reverse only) and it was drivable although steep hill starts were really not good given the work the poor torque converter was being subjected too, no choice in this matter as I did not fancy walking home ( ! ) , a very distinct lack of acceleration is expected too obviously but once it starts to move and you're up to about 20mph its OK.

This is too much information I expect sorry

I'd go with having the codes read via Lexia/Diagbox and see what the actual cause is before making a decision. It could unfortunately range from anything from a tiny wiring fault (dirty multiplug even!) to a complete transmission needed, with anything in between. I'd be slightly wary if the owner said a garage condemned it as some garages do not like to touch auto transmissions at all... "sealed for life mate / take to the dealer" kind of thing.

Regarding code reading, I can't recommend a generic code reader for this purpose as it is likely to not get *all* the codes for this type of issue.

[xantia_v6]

It is usually OK to drive a 4HP20 in limp mode, but it depends on the cause of the underlying problem.

Limp mode cash be triggered by a detected slippage in the internal clutches (not so good), or by sensor failure, or failure of the geasr selection switch. In limp mode you get 3rd gear and reverse gear, nothing else. Pulling the fuse just gives you limp mode (so blown fuse is another cause).

BTW.. Limp mode is reset every time the ignition is switched on, so if the transmission immediately goes into limp mode before Bering driven, it is likely to be an electrical fault rather than mechanical.

[Mandrake]

For £650 with a known faulty gearbox I would stay away.

I say this as someone who struggled for nearly 2 years with a failing 4HP20 which eventually did fail despite my best efforts to save it. It got to the point where I would not drive any significant distance from home for fear of it failing and stranding me far from home. (In hindsight I was correct to worry about this)

You might get lucky and find its an electrical fault, but chances are at least even that even if the cause of the current limp mode is an electrical fault, there may be additional underlying mechanical problems.

While it is "OK" to drive in limp mode for short distances at lower speeds (I think something like a maximum of 50mph for 50 miles with no hard acceleration is quoted) you should be aware that in limp mode the torque converter is permanently unlocked and thus generating maximum heat, and this can easily result in the oil and/or clutches overheating if the car is driven hard/fast for long periods of time in limp mode.

When the ECU has control of the gearbox it tries to lock the torque converter up most of the time - this is done for fuel efficiency but a side benefit is it dramatically reduces heat production in the gearbox compared to an unlocked torque converter with a ~600 rpm slip.

The ECU also monitors the oil temperature and when it goes above a certain point (about 105-110 degrees from memory) it goes into an emergency temperature control strategy where it locks the torque converter up as much as absolutely possible even under conditions that it would normally allow it to slip. This affects the driveability and performance of the car (mainly at lower RPM in each gear where you will lose a lot of torque without the torque multiplication of the torque converter) but cools the oil and prevents the gearbox overheating.

In limp mode the ECU has no control over the gearbox (indeed the ECU may not even be functioning if it has lost power) so the torque converter stays unlocked and the gearbox in 3rd gear, which if you push the car hard will overheat the oil. If the car has been driven for a long time in limp mode and not driven cautiously mechanical damage to the gearbox is possible and I would not touch it even if the limp mode fault can be repaired.

Just my 2c worth.

[Mandrake]

I'd go with having the codes read via Lexia/Diagbox and see what the actual cause is before making a decision. It could unfortunately range from anything from a tiny wiring fault (dirty multiplug even!) to a complete transmission needed, with anything in between. I'd be slightly wary if the owner said a garage condemned it as some garages do not like to touch auto transmissions at all... "sealed for life mate / take to the dealer" kind of thing.

Regarding code reading, I can't recommend a generic code reader for this purpose as it is likely to not get *all* the codes for this type of issue.

You won't be able to read a 4HP20 in a Xantia with a generic code reader at all - only a Lexia or Elit will do.

[RichardW]

Car is in Sweden,so £650 might be v cheap - don't know about prices over there.

Worst case it needs a box re-build / replacement. Cost that out, add it onto the cost of the car and then decide if the finance works out for you; and you are prepared to do work / want the car badly enough.

[CitroJim]

Get a Lexia on it first and see what's wrong... A limp fault on an HP20 is rarely internal or mechanical.

It may be a bargain...

[spider]

I'd go with having the codes read via Lexia/Diagbox and see what the actual cause is before making a decision. It could unfortunately range from anything from a tiny wiring fault (dirty multiplug even!) to a complete transmission needed, with anything in between. I'd be slightly wary if the owner said a garage condemned it as some garages do not like to touch auto transmissions at all... "sealed for life mate / take to the dealer" kind of thing.

Regarding code reading, I can't recommend a generic code reader for this purpose as it is likely to not get *all* the codes for this type of issue.

You won't be able to read a 4HP20 in a Xantia with a generic code reader at all - only a Lexia or Elit will do.

That's what I said.

Get a Lexia on it first and see what's wrong... A limp fault on an HP20 is rarely internal or mechanical.

It may be a bargain...

I concur. As put earlier it might (if lucky) even be something silly like a corroded multiplug or the like causing it all.

[Mandrake]

I'd go with having the codes read via Lexia/Diagbox and see what the actual cause is before making a decision. It could unfortunately range from anything from a tiny wiring fault (dirty multiplug even!) to a complete transmission needed, with anything in between. I'd be slightly wary if the owner said a garage condemned it as some garages do not like to touch auto transmissions at all... "sealed for life mate / take to the dealer" kind of thing.

Regarding code reading, I can't recommend a generic code reader for this purpose as it is likely to not get *all* the codes for this type of issue.

You won't be able to read a 4HP20 in a Xantia with a generic code reader at all - only a Lexia or Elit will do.

That's what I said.

No you said its likely to not get all the codes - but in fact a standard OBD-II code reader will not communicate with the gearbox at all or any other ECU in a Xantia as a Xantia is not OBD-II compatible despite using a standard OBD-II connector.

So trying to use anything other than a Lexia or Elit is a complete waste of time on a Xantia.

[spider]

No you said its likely to not get all the codes - but in fact a standard OBD-II code reader will not communicate with the gearbox at all or any other ECU in a Xantia as a Xantia is not OBD-II compatible despite using a standard OBD-II connector.

So trying to use anything other than a Lexia or Elit is a complete waste of time on a Xantia.

Sorry for the misunderstanding.