Wheel speed sensor and outside ambient temperature issues (Help!)

carabuser

Sergeant
Oct 2, 2019
257
162
0
UK
Ride
Z4 35i & 335i
Took my car to a shop today for walnut blasting and OFHG replacement. The shop is an hour away and about 5 minutes from home on my return journey I had the ABS light and a couple of other related lights pop up, then disappear. Then about a minute later it did the same and cleared itself again.

Scanning the fault codes shows 2FE7, 5DA1 and 5DA0 which are all related to the front right wheel speed sensor. I also noticed that the outside temp was reading 22C on the dashboard when it's actually closer to 10C here. After shutting the car off the temp started dropping quite quickly back to the correct reading of 10C. I'm 100% sure the ambient temp sensor was working prior to this.

Normally I'd just go back to the shop and get them to sort it out, but its an hour away and closed for the weekend now. I've been out and stripped the car down a bit so I can look for obvious issues around the engine and noticed that the junction box under the intake manifold is hanging loose, not attached to the manifold so I'm thinking that if both sensors are routed through this JB then I need to remove the intake manifold and inspect all the wiring.

TL: DR
Are both the front right wheel speed sensor and the ambient temperature sensor both routed through the JB under the intake manifold? And does anyone know the full cable routing for the front right wheel speed sensor and can suggest where it could have been damaged?
 

NoQuarter

Major
Nov 24, 2017
1,605
1,003
0
Indiana, USA
Ride
Z4 35is, 535xi, X5 35i
I think you may be reading too much into the coincidence.

I know it is hard not to but I don't think you will find anythinratelated to those issues under your intake manifold.

That box left loose is pretty common
 

carabuser

Sergeant
Oct 2, 2019
257
162
0
UK
Ride
Z4 35i & 335i
Yeh I think you're right. I found some diagrams showing with harnesses on realoem and there's no overlap between the ambient sensor and wheel speed. They wouldn't have been in the same area as the wheel speed sensor so I'm just going to put a new one in. The ambient temp thing hasn't reoccurred, not sure what's happening there but I'll keep an eye on it.

I did remove the throttle and properly re-attach the junction box and put everything back together. They did a good job of cleaning the oil leak from the OFHG so I'm happy with the work done by them.
 

1and1

Specialist
Dec 28, 2016
60
34
0
Tally, FL
I just recently played the ABS wheel speed sensor game.

I'd suggest replacing both front sensors at the same time. I did one (right side) and within a few miles the variance between the two was enough to trigger a fault from the other side. Replaced the left and all was right.

FWIW, my rears failed within 1000 miles after the fronts...
 

TheFixer

Corporal
Aug 16, 2020
242
128
0
Tennessee
Ride
2008 535i, my wife
Sometimes these kinds codes and things not working right happen due to voltage irregularities. Especially if you get dash warning lights that pop up for just a second and disappear. These cars are notorious for that.

If your battery starts to go bad you'll get all kinds of unrelated codes. If it's not programed to the car properly same thing.

Most recently I had intermittent tranny codes popping from my voltage regulator going bad. I'd get the gear icon flash in the display with a cel and it be gone before I could blink. Would just randomly happen but the car was driving fine.

Anyway, easy to check battery voltage and what the alternator is putting out by using a scan tool, multimeter or the hidden menu in your dash.
 
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MoreBoost

Sergeant
Jul 27, 2017
334
135
0
Ride
335i
My wheel speed sensor failed the day after I got my car back from having Turbos replaced. Drove home fine. Might just be cold weather related.

Have tested the sensors with INPA and all are reading the same so I'm not going to replace any other unless they go dead.

Maybe the temp sensor got knocked loose and is near a coolant hose\radiator
 

carabuser

Sergeant
Oct 2, 2019
257
162
0
UK
Ride
Z4 35i & 335i
The ambient temps have been fine since. I'm thinking it could be related to me clearing fault codes with ProTool, I'll test it out when I fit the new wheel speed sensors.