ABS light and gearbox issue P0501 code

[Gareth1984]

Hi all i am new here an i would really appreciate some advice or help.

My C5 has developed an issue that is affecting the gearbox.

I have had the ABS and traction light come on and since that the gearbox is very erratic. Basically i can drive the car at low speeds with no issues but as soon as i put my foot down i get a big clunk into gears and sometimes shifts down. I plugged the car in to my very cheap
And basic code reader and i get a code P0501 which reads wheel speed sensor passenger side. I’ve tried swapping the sensors over but it still shows the same code and wheel.

I’ve erased the codes but the problem with the gear changes still persist and the lights come back on almost instantly.

I have it booked in this week at an auto specialist but i wanted to see if i could get some advice to pass on to them. Unfortunately I don’t have any fancy plug in devices so i am unable to give any more codes or information.

Ultimately the answers I’d like is Does this Sound like the gearbox or could it be something to do with the ABS side of things.

Many thanks

[srichards]

Has it been used much? Is it on a battery charger? If it hasn't and isn't on a charger I'd probably try trickle charging the 12v battery first and then rechecking. Low voltage 12v can cause lots of gremlins.

[Mark-RS]

If you are local to me I'm happy to plug it in and read it ? I'm on northants.

[Gareth1984]

Thanks guys I’m in Leicester not sure how far northlands is but I appreciate the offer.

I’ve not used it much at all and funny enough the battery is rubbish i have literally got it on charge now. However i did buy a new battery 6 months ago and that didn’t solve it.

[Gareth1984]

What postcode is northants. I can check my distance then.

Thanks

[Mark-RS]

You are about 40 mins from me from me if that's any help. These cars don't seem to like being sat around much, it seems those that drive them lots get less issues than those that use them sparingly.

[Gareth1984]

Thanks Mark I’d appreciate it if you didn’t mind plugging it in for me. I do have it booked in tomorrow so if i do not have any joy with that I’ll be in touch.

I fully agree about not using them leaves more issues. When i was using it daily it was faultless, now I’ve got this issue after sitting for a while

[srichards]

Ctek do a battery conditioner. You can get a cigarette lighter adaptor for it so you can just plug it into the accessory socket and leave it like that without faffing with the boot or using the posts under the bonnet. I leave the window slightly open for the cable. It takes seconds to disconnect as well.

I had weird gearbox behaviour with mine. It was the F125 switch. I also found a non Bosch battery also seemed to upset it even more. It was definitely less unhappy once I put a proper battery back on it.

[Gareth1984]

That’s interesting because the battery has never been the same since it was replaced from a bosch one.

What is an F125 switch.

I forgot to mention as well that some of my wiring is not the best and a previous garage cut out a little black connector and wired the wires directly by soldiering them.

The box removed has some numbers on

1J0 973 724 >PBT<
FEP 2/2 4799

Any ideas what this box is. It was causing the car to stall because the wires were melted and touching so the garage decided to wire it directly. Thinking back now it was not right much longer after that

[Shoppinit]

1J0 973 724 is the part number for a connector.



Looks like a MAF sensor connector but it could be other stuff. An idea of where this frankenstein "repair" took place would be useful. Not sure I'd take my car back to them if they did that.

P0501 is for the vehicle speed sensor. Since it's a generic code, though, I would definitely want a VAG error code to be sure.

[srichards]

F125 switch is the gearbox range sensor. When it goes wrong you get thumpy gear changes. Mine thumped a few times and then thumped into reverse one day just after starting up and gave me the gearbox warning lights of doom. Restart the car and it often goes away but the more you drive it like that the more damage you can end up doing.

I think it needs a visit to a specialist to undo any bad work that's been done before as well as check out the current issue.

[Gareth1984]

Yes i have it booked in tomorrow at a reputable auto transmission specialist. My biggest regret was using that awful garage to have work done in the past, it’s no longer there now which is no surprise.

I will update tomorrow when the garage have given me some idea of what codes it’s reading and what they suggest.

Thanks all i really appreciate the response.

[srichards]

When did it last have a gearbox oil and filter change? That's also worth doing if it hasn't had one in a few years. That also shows the state of the gearbox.

[simonpoulton]

If this is any help, before I changed my MAFs I was getting the traction control kicking in on spirited acceleration. The light would flicker and eventual stay on, as well as what felt like clunking. Gear changes were not great either. Replaced the MAFs and all was good. I believe the MAFs are used in the engine load calculation, which is then used in a few places like the gearbox ecu and traction control. If it's been coded sensibly, then it would use the engine load calculation to work out how hard to change gears.

[Shoppinit]

Good shout. And especially since it looks like his MAF wires melted. If it wasn’t for the p0501 code I’d say it was a sure thing. That’s why we need the vag codes.