2015 Skoda Octavia 1.6 D   4x4

 

At a total loss and looking for advice please. I've had an intermittnet loss of brakes , when my engine is cold and I'm heading downhill.   I press the brake pedal  and its solid and the car just doesn't slow down, I literally had to stand on it last time it happended, then used my hand brake as I was heading for a group of people!  The engine management light comes on each time. I switch it off and back on again and alls fine with the brakes working again and the engine warning light goes out.

I now cannot drive my car, its too dangerous . I had it in to my local garage who are great, but after it happened to one of the mechanics once, they were unable to replicate it again over a 5 day period. They say they checked the servo pipes and there were no leaks and no loss of pressure in the servo?. There are no faults showing when they run a  diagnostics checks..

 

I have now had it towed to my local Skoda dealer who have driven it in different conditions (hot/cold) over 125 miles and its not happened again. I have totally lost faith in it and want to trade it in but no way would pass on such a potentially dangerous problem to someone else. I'd rather scrap it!!!

If the gargage can't find the fault I have no idea what to do, The Skoda garage said they could replace the servo, pipes etc andt may not be able to guarantee it won't happen again......I'm community health staff and need a reliable car quickly......I would really appreciate it if anyone has any advice on what I should do next. 

 

I had a major coolant leak which cost £1,600 to fix last year and also now have a water leak in my passenger footwell.......... and  have really gone off Skodas!!!   HELP please

Had a very similar experience in my Octavia. It had been a while since a full brake bleed so had that done and it never happened again (happened 3 or 4 times up to that point).

 

A bleed is relatively cheap so could be worth a shot. Although I understand that doing a bleed on the off chance may not be the route you want to take due to your work.

Thanks so much for your reply, I'm pleased yours is fixed.  I'm happy to try anything at this point. For someone who once changed the cylinder head gasket on an old Honda Civic, I have absolutley no idea where to start with modern cars!..... Very frustrating. I'll let you know how it goes.

Brake bleeding will achieve nothing other than perhaps give you a spongy pedal to offset make things even worse, the problem is vacuum (not pressure) related, either the vaccuum pump, a leak elsewhere (but I think the servo has a seperate vacuum accumulator) the servos itself or an intermittent blockage/leakage from the vacuum hose or a union.

Edited 21 June, 20214 yr by J.R.

3 hours ago, J.R. said:

Brake bleeding will achieve nothing other than perhaps give you a spongy pedal to offset make things even worse

 

I disagree, if the brakes have been badly bled in the past leaving air in the ABS unit it can cause strange braking issues including loss of brake effectiveness with a hard pedal.

 

But I do agree it sounds more like a servo assist problem. If it is lighting the CEL then there should be fault codes logged in the system. That is where I would start. 

Hi,

From my experience with my car, there could be several reasons:
1. The brake fluid reservoir tank has small pin which it sits on which allows the pump to pump fluid from it. If the tank isn't sitting straight, the abs pump continues to pump fluid to the brake line but can't extract it back. The brake fluid continues to be added more and more until there is no more room, making the brake pedal very hard to press.

2. The brake fluid hasn't been bled well, leaving old fluid in the system. The old fluid continues to receive moisture, making itself more viscous and hard to move inside the system freely.

 

I've attached a picture how it was in my car when the abs pump was failing to due misaligned pump reservoir with a broken pin.

 

Edited 24 June, 20214 yr by Matanfr

@Elsie21

Any update?

?

Had the car had one brake fluid change yet or even the 2 that the Manufacturers recommend, 

then on another subject has your Haldex got a record of an Oil change, and recently a 2nd one, or a service with a cleaning of the filter / pump for the Haldex.

That is the brake master cylinder and not the ABS pump.

 

"The brake fluid hasn't been bled well, leaving old fluid in the system. The old fluid continues to receive moisture, making itself more viscous and hard to move inside the system freely."

 

Either you are not being serious or have a fertile imagination.

 

I can recommend the VW self study programme 374 for a comprehensive understanding of the ABS, traction control and assist systems and their interactions with each other.

5 hours ago, Matanfr said:

The old fluid continues to receive moisture, making itself more viscous

Since when?

 

There is a known issue with brake fluid being hygroscopic yes, but that is that the absorbed water lowers the eventual boiling point of the system.

Edited 24 June, 20214 yr by KenONeill

'Hygroscopic' even!

32 minutes ago, e-Roottoot said:

'Hygroscopic' even!

Changed, but still comes up as a misspelling.

 

Appreciate everyones advice. Skoda have now had my car for 2 weeks and are drinving it daily. They have now clocked 220 miles under different conditions with different drivers but have not yet managed to replicate the fault. They say that it has to replicate before they can fix it, which makes sense. otherwise, there are so many possible things that can create this fault that it would potentially cost thousands to replace everything in the hope that it wouldn't happen again, but with no guarantees.

I went in Friday and asked what I'm supposed to do if they can't replicate it, but they were understandibly at a loss. They recommended trading it in, but as I said, I'm not prepared to hand over a car to someone with a dangerous problem. They said that folk buying it, or a gargage, would check it over first , but I pointed out that  thats what they're doing and nothing is showing up!!! My husband also thinks I should trade it in, but when I asked him if he'd be happy for our family to drive it, he said no.....

 

The car has been serviced regularly so I assume that brakes/ fluid  and oil have all been checked/ changed . but will look into it. Thanks.

 

 

13 minutes ago, Elsie21 said:

Appreciate everyones advice.

Sorry we can't help more. My best shot for a "hard brakes" issue is a problem with the servo leaking vacuum or the vacuum line that feeds it being blocked. Actually, that gives me an idea. If that line is externally fabric armoured rubber, there is a known failure mode where it collapses internally, resulting in a loss of vacuum and hence of the servo assistance function. If there is such a line, then if someone squeezes it, it will feel squidgy.

Didn't happen with Octavia, but with many previous cars I've been able to replicate the issue deliberately, when driving slowly down with very little RPM. I could press many times brake until it stiffens and stops braking, exactly as you describe, but it takes just a couple of seconds to re-gain the pressure in the system. Is it possible that something similar occurred when you was experiencing it, but the dealers if drive it with more spirit, cannot do? Just an idea...

 

It's really a cold shower when you press stiff pedal and nothing is happening. I can imagine how frustrating and dangerous it is.

7 hours ago, Elsie21 said:

 

 

The car has been serviced regularly so I assume that brakes/ fluid  and oil have all been checked/ changed . but will look into it. Thanks.

 

 

 

I would not assume this at all. Regular service is usually a simple oil change and maybe a fuel, air or pollen filter. Many garages or dealer won't check brakes unless specified by the customer.

However it sounds like the usual checks have been done in this error search so should be ok.

2 hours ago, nidza said:

I could press many times brake until it stiffens and stops braking, exactly as you describe,

Easy explanation; you braked so much and so often that you drained all the vacuum out of the servo, and the engine/vacuum pump took a few seconds to rebuild vacuum.

No had just started my car and had barely used the brakes. It always happens when its cold.

 

Update:  Skoda garage are being very helpful but have now driven my car 300 miles over 3 weeks and the fault has not replicated. They have offered me another week of testing but thats it...and I really dont blame them. It can be 1-2 months between loss of ABS  . I now have to decide what to do with a car thats only appraoching 6 years old.

I have been told that driving a car with a known potentially dangerous fault will invalidate my insurance, plus its just crazy to drive a car with dodgy brakes.

 

Am all out of options and am considering just cutting my losses and selling it for spares or repair.

32 minutes ago, Elsie21 said:

Am all out of options and am considering just cutting my losses and selling it for spares or repair.

 

I don't know why you don't just take t to a good indi and get them to do a proper brake fluid flush and change using the proper equipment at the proper pressures, then do a fault scan and reset faults. Dealers are often just fitters and useless at fault tracing.

 

As I said above if it has lit the CEL it will be logged along with many parameters and can be looked at using either the dealer system or VCDS.

 

As others have said Brake fluid is NOT part of the servicing. It is recommended and offered as an additional service like aircon re-gas. It could have a full dealer service history and 6 year old brake fluid.

I'll get them to do the brake fluid flush, happy to try anything.  I have no knowledge of modern car engines and this may be a stupid question, but can you  still trace faults if theyve already been cleared?

As @flybynite says. A full dealer history just means the car hasn't been taken anywhere else. Doesn't mean it's had all the necessary maintenance done or even to a good standard. Just means it's been recorded in one place.

 

good shout getting the fluid done. It will at least clear one possiblity.

4 minutes ago, Elsie21 said:

his may be a stupid question, but can you  still trace faults if theyve already been cleared?

 

Not a stupid question at all, Depends on the code but generally if it has been cleared then it is gone. If a dealer tech has cleared it without recording it they want shooting.

 

One reason I scan all of my cars before they get within smelling distance of a dealer service centre.

2 hours ago, Elsie21 said:

can you  still trace faults if theyve already been cleared?

No. That said, if the actual fault hasn't been repaired, the relevant code will recur.

I'm having this exact problem, identically to how the OP describes it. Any resolution to report, @Elsie21? Thanks. 

@Elsie21or @No.733 have you managed to get your car fixed? I've got the same bug here.

I’ve heard/read about the same issue in VW forum - it was related to a vacuum leak in break booster vacuum hose and check valve.

 

Some were reporting that pressing the gas pedal fixes the brakes. Hope this helps, sounds like a scary issue to me!