98 Audi A4 Quattro 2.8L Won't Go In Reverse

[FlyNikolai]

Smh, okay so I was told by a mechanic to get an engine wash to help with the inevitable oil leaking of this car. So It sounded like a great idea because I just got the car and everything was really dirty from over the years.

So I went to a local Car wash that does engine cleans, and I got the engine and chasis washed. Now my car won't go in Reverse. Park, Neutral, and Drive works...but when I put it in reverse the cluster says Neutral smh.

Payed $60 with intentions to help my car and end up messing it up. Car was working fine before the wash, so it must be electrical from a logical guess.

This is my first car and I've done some research on the issue...most saying the neutral safety switch, TCM etc. Hoping everything dries and will be okay & isn't a serious transmission problem.

Any ideas would be greatly appreciated, thanks guys.

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[Nollywood]

Since this all happened after a wash...

What is your PRND4321 display like? Does it show gear selected, or is the whole display lit up?

[FlyNikolai]

Since this all happened after a wash...

What is your PRND4321 display like? Does it show gear selected, or is the whole display lit up?

It shows gear selected. It shows when I'm in Park, Neutral, Drive, Tiptronic works. Gears 4,3,2,1 says D when selected, not sure if its supposed to select those specific gears as I've never used them before.

But when I gear into reverse it displays it as Neutral.

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[Nollywood]

I would say your F125 switch (Transmission Range Sensor) has either failed, or the connector is contaminated by moisture and / or oil.

I would start by unplugging it, giving the terminals in the connector and on the switch itself a good clean with brake cleaner (aerosol type). Then spray both with contact spray, and replace. Test. If there's no change, replace the switch.

[walky_talky20]

Sometimes, the fault is temporary, but the car will not return to proper operation without connecting and manually clearing the fault code with VCDS. That may be all you need to do. I've seen that happen more than once.

If that doesn't fix it, or the fault comes back, it is probably the switch. The switches are really expensive. If you're a cheapskate (or just a DIY'er) you can drill the rivets of the switch to get it apart. Careful not to loose the fiddly bits or how they go together. Springs and what-have-you. Then clean the water/contamination out of it (often from a coolant leak). Maybe redo the dielectric grease. Slap it back together with some small bolts and nuts (or new rivets if you're, like, super confident in your work!) and see how you did.

[FlyNikolai]

I would say your F125 switch (Transmission Range Sensor) has either failed, or the connector is contaminated by moisture and / or oil.

I would start by unplugging it, giving the terminals in the connector and on the switch itself a good clean with brake cleaner (aerosol type). Then spray both with contact spray, and replace. Test. If there's no change, replace the switch.

Alright thanks appreciate the help

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[FlyNikolai]

Sometimes, the fault is temporary, but the car will not return to proper operation without connecting and manually clearing the fault code with VCDS. That may be all you need to do. I've seen that happen more than once.

If that doesn't fix it, or the fault comes back, it is probably the switch. The switches are really expensive. If you're a cheapskate (or just a DIY'er) you can drill the rivets of the switch to get it apart. Careful not to loose the fiddly bits or how they go together. Springs and what-have-you. Then clean the water/contamination out of it (often from a coolant leak). Maybe redo the dielectric grease. Slap it back together with some small bolts and nuts (or new rivets if you're, like, super confident in your work!) and see how you did.

Okay I will definitely try clearing the code first, thanks for the help really appreciate it

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[FlyNikolai]

Hey so I have an update guys...so I connected the VCDS. I wiped the code, now all the gears on the display are lit (LIMP mode from my research?) But the cars goes in reverse now, all the gears work. Any ideas what I should do next?

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[Nollywood]

What was the code stored?

[FlyNikolai]

What was the code stored?

Hey sorry about the late reply, I have to be more specific now lol. I let my dad check it out for me I thought he went the VCDS route but apparently he didn't.

He told me his friend that's a mechanic hooked up a reader to it, he's not even sure what kind of reader. But after the reader that's when all the lights came on the display with all the gears selected and reverse working again.

I noticed that it shifts very hard into reverse, does AutoZone do VCDS scans? I'm scared to drive on it again from what I heard from research...

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[walky_talky20]

VCDS [Lite] is free. All you need is a PC laptop (any old XP clunker will do), and a $9 cable from eBay. That is enough to read and erase codes from the Transmission Control Module on your A4, as well as looking at the sensor readouts from that module (ie: gear selector position, etc). It does way more cool stuff, too.

If you intend to service electronic faults on your Audi by yourself (instead of just dropping your car off at the dealer and paying the moneys, like normal people do), VCDS is basically mandatory. Generally speaking, no other scan tool you will have access to will even come close. Free code scanning at parts stores is generic engine emissions codes only. In this case, you require Manufacturer-Specific transmission code reading and clearing, possibly for codes that are only soft-set (pending). AutoZone can't touch this stuff. So spend the entire 9 bucks and get joe'self in on some of that action.

Hard shifting is expected during limp mode. Line pressure is static and you are probably limited to just 2 gears: Reverse and 4th gear (slug mode).

[FlyNikolai]

VCDS [Lite] is free. All you need is a PC laptop (any old XP clunker will do), and a $9 cable from eBay. That is enough to read and erase codes from the Transmission Control Module on your A4, as well as looking at the sensor readouts from that module (ie: gear selector position, etc). It does way more cool stuff, too.

If you intend to service electronic faults on your Audi by yourself (instead of just dropping your car off at the dealer and paying the moneys, like normal people do), VCDS is basically mandatory. Generally speaking, no other scan tool you will have access to will even come close. Free code scanning at parts stores is generic engine emissions codes only. In this case, you require Manufacturer-Specific transmission code reading and clearing, possibly for codes that are only soft-set (pending). AutoZone can't touch this stuff. So spend the entire 9 bucks and get joe'self in on some of that action.

Hard shifting is expected during limp mode. Line pressure is static and you are probably limited to just 2 gears: Reverse and 4th gear (slug mode).

Wow you're awesome thanks man, I should have some fun with this then.Because I'm a Computer Technician what a coincidence lol, so I literally live for stuff like this.

Thanks I really appreciate it you are very helpful, because I find it ridiculous how the shops try to charge you hundreds just for diagnostic tests smh.

One more question, seeing that my problem looks pretty much electrical, am I hurting my transmission in any way when I drive?

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[FlyNikolai]

Also can you guide me to the right cable to purchase? Would appreciate it

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[FlyNikolai]

Ordered the "blue cable" should be here tomorrow...will update. Thanks again guys

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[walky_talky20]

No, you won't be hurting anything to drive it in limp mode. The most unhealthy thing is the hard slam into Reverse. It isn't going to break anything, but it isn't helping anything, either. Various bushings, motor/trans mounts, axles, differential, etc. might be getting being stressed a little there.

[FlyNikolai]

Hey so I scanned my car with VCDS earlier today on my laptop and this was the only code that came up (attached image below). I cleared code but it just keeps coming back. Is there an easy way to dry or troubleshoot this part? Code was 00293 Multifunction Switch F125 Implausible Signal

I did some research, but I'm still not exactly sure where it's located. Thanks guys

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[elduderino200]

This is what you need right? It doesn't look too terrible if you've got the tools.

http://www.audiworld.com/forums/a4-b...riteup-333745/

Every picture is ultra zoomed-in, so I'm not sure where exactly this is on your car (aside from underneath the transmission and near the left front side).

[FlyNikolai]

This is what you need right? It doesn't look too terrible if you've got the tools.

http://www.audiworld.com/forums/a4-b...riteup-333745/

Every picture is ultra zoomed-in, so I'm not sure where exactly this is on your car (aside from underneath the transmission and near the left front side).

Yes thanks I saw this, just was hoping for an easier way to do it or just dry it. As this is my first car so I'm not that skilled yet...learning lol, but I am very much a DIY'er. Just trying to see how I'm going to approach this...

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[elduderino200]

Regarding the specific part: I have 0 experience with it sorry :( Hopefully you can just take the sensor our and dry it (but in my opinion I don't think you'll be that lucky, especially with it coming back after clearing).

Regarding the DIY: do some research on how to take it apart (sound like you have already), set aside an afternoon, then get some friends to come over and help. The extra eyes and hands will make it go faster and be easier.

[walky_talky20]

If it were me, I wouldn't be buying a new switch right away. The switch is not some complex electrical part with chips and circuit boards. It is literally just a rotary switch with various points inside that contact or break depending on the position. It just got some water in it and that water needs dried out. You might even be able to heat it up in place with a hair dryer for 5 or 10 minutes. I've not tried that, but I guess it's worth a shot. If that didn't work, I'd pull the switch take it apart, clean/regrease, reassemble and then rock out (you know how I do).

In any case, the switch is very likely 100% save-able. That's what I'm saying.

[FlyNikolai]

Regarding the specific part: I have 0 experience with it sorry :( Hopefully you can just take the sensor our and dry it (but in my opinion I don't think you'll be that lucky, especially with it coming back after clearing).

Regarding the DIY: do some research on how to take it apart (sound like you have already), set aside an afternoon, then get some friends to come over and help. The extra eyes and hands will make it go faster and be easier.

Thanks, I plan on trying to fix it this weekend

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[FlyNikolai]

If it were me, I wouldn't be buying a new switch right away. The switch is not some complex electrical part with chips and circuit boards. It is literally just a rotary switch with various points inside that contact or break depending on the position. It just got some water in it and that water needs dried out. You might even be able to heat it up in place with a hair dryer for 5 or 10 minutes. I've not tried that, but I guess it's worth a shot. If that didn't work, I'd pull the switch take it apart, clean/regrease, reassemble and then rock out (you know how I do).

In any case, the switch is very likely 100% save-able. That's what I'm saying.

Yes I will definitely try the blow dryer technique this weekend. I cleared the code last night and it came out of LIMP mode, so I just let the car sit overnight and will see what happens today. I'm also on the same boat as you, I really believe the switch is 100% fixable without needing a new switch.

Car was perfectly fine before the wash. Thanks though, you give me so much hope lol...I will update this weekend when I work on it.

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