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996 4S Steering angle sensor issues?


16 Oct 2018
Afternoon all,

Apologies - got another issue with my 4s bringing out of hibernation.

Long story short.. dropped car at local garage to have steering rack and lower arms replaced.

No errors.

Turned out a new rack wasn't needed (old one got to the stage of being about half removed), when the car was put back together a steering angle sensor fault has come up.

Now, I've got them to replace the battery in case it was a low volt issue, this hasn't rectified it.

From what I've understood, plugging in a reader is showing no change in values coming from the sensor.

Only thing I cant confirm is if the car has been driven over 6mph since the battery change (reading some of demorts posts that is a key figure?)

Any other ideas? Or ideas how working on the rack might have affected the sensor - or just bad timing? As I understand it, its accessed from inside the cabin and if so they wont have been anywhere near it.
Any thoughts on this before I take a plunge a new sensor (well used / salvaged sensor) I think I have found the correct one for sale in Germany at aroud 1/4 cost of buying a new one.
My guess is they haven't put the steering wheel back in the position where it originally was, but instead have put it on a few splines round so it is on straight in the dead ahead position, but as far as the rack is concerned the dead ahead position has changed.
This would happen if the track rod ends were refitted differently (even very slightly differently) to before they came off. Even if they weren't removed, just moving the position of the rack slightly might do the same.
The problem, then, is the steering angle sensor thinks the car is turning, but the ABS sensors (and the driver) know it's going straight.
I'm guessing the remedy is a four wheel alignment and a steering angle sensor reset.
Many thanks, I'll mention this when I drop the new exhaust off today.

Would be nice to avoid having to get a new sensor / avoid throwing parts at the car that it doesn't need. Given the area in which the sensor is located, it would have to be a hell of a coincidence for it to fail at the exact same time they were working on the rack. I'm hoping and optimistic it's just as you describe.

I did leave them with new track rod ends as well as the rack (which didn't get used) every chance they have replaced the ends anyway which would add to the scenario you describe.

I think what they have struggled with is the reset, I'm assuming it needs some specialist kit in order to be able to do this?
Popped to the garage at lunch with the new exhaust and had a chat.

Turns out, the sensor is giving a reading, but it's not changing when steering wheel is moved.

They are going to try and have a look tomorrow and see if the inner ring of the sensor isn't turning with the shaft, by the sound of it, the angle sensor is in a metal box by the pedals. Any easy way of getting to it?

I'm afraid I don't know the answer to your questions. The scenario I described is a generic one for cars with a steering angle sensor. It happened to my wife's Nissan Juke! (where it caused the traction control to randomly cut in :roll: after I'd replaced a suspension control arm ). Fixed by tweaking the tie rod ends to 'straighten" the rack.
Not a problem, appreciate the input.

Turns out a new (well salvaged) steering angle sensor didn't rectify the issue.

Car is being trailered to Wrightune in Oxford tomorrow to hopefully sort it out!

Doesn't sound like an issue they are familiar with though after a quick chat with them.

Will update once remedied incase it comes up for anyone else on future.
I would start with a vehicle handover via a tester ..

Steering angle sensor talks to the PSM control unit .. you have the possibility of damaged wires perhaps ..

A fault code readout of the PSM would help .
Many thanks demort, as always much appreciated.

Had a chat with Wrightune on Friday but they haven't had a chance to look at it yet.

Out of interest, is any of PSM wiring in the front sub frame area? Would be the most likely place I can think where damage may have happened whilst the rack was being worked on.

No codes to share yet unfortunately, I'm hoping Wrightune manage to sort it without an eye watering parts bill at the end.

Originally was hoping I could assist the non specialist (but great guys) garage that it was first at with the diagnosis avoiding the logistical faff of getting it delivered to a specialist.

If the battery was disconnected you will get a steering angle sensor fault but once driven over 6 mph it will clear.

They have put a tester on the car and it shows a static reading which does not alter when it should ..

Imagine a round disc with 100 holes in it on the outer edge .. a light will only shine through a hole when its lined up .. the car can count the holes in either direction so it knows the position of the steering .. that's an analogy of how it works .. a disc with holes in it .

A calibration of the steering angle sensor is the first point of call which is done with a tester , in calibration mode you turn the wheel 20 degrees both left and right then center the wheel .

A vehicle hand over would be next just in case a control unit is messing around .. this is like turning your computer off then on after it crashes .

Fault code readout will say if the car is seeing any faults .. a wiring issue with the sensor and you will get open circuit fault codes .

The PSM is inside the front tub with the steering angle sensor being inside the car and on the steering column ..

It's a bit difficult to damage it or the wires but i don't know what they did to remove the rack .. you undo the joining bolt on the column from under the car but perhaps something pulled on the shaft :dont know:

It's a coincidence that its now failed after this work but it may be unrelated .. diagnosis will say there when the fault is found .

The sensor itself .. i just looked it up .. eye wateringly expensive to say the least .. porsche are profiteering on this part that's for sure !

If they have fitted a second hand one then logically it won't be this but i don't think they have driven the car or done a calibration so it may well be either of these .

Btw to replace this sensor you have to remove the steering column and separate it to get the sensor off .. not 5 mins of work there !

Image below of the part .


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Many thanks again for the detailed response!

When trying to assist the local garage, we were trying to find anything we could online about how it works/what could cause errors etc/calibration process.

I'm not sure exactly what code reader the garage has or if it was able to do the calibration mode on it. I'd mentioned about the 6mph, and it should have gone over that driving between the storage area at the back of the workshop and the front.

I'd supplied the second hand sensor, breakers yard £200 all in (and can return it fortunately!). Yes prices are crazy and the 4s sensor is harder to come by than 986/C2 part it appears.

Local garage had already removed and refitted the original sensor once to give it a once over /make sure its turning with the column.

The last test I got them to do before sending the car off to the specialist was to plug the 2nd hand sensor in (but not fitted to column to avoid unnecessary time/ labour) to see if any change in values through the reader could be read when turned. If so, they were going to swap it over, if not off to the specialist - which is where we are now.

Hadn't heard of handover before, reassuring to know there's a few other avenues to try before things get expensive.

Usually I'll try and do all of the work on my own and be in the position to feedback all of the information first hand, quite frustrating/tricky trying to do it 2nd/3rd hand.

The other thing the specialist had mentioned in passing was that an ABS/PSM fault was now present. I'd assume this is related to the angle sensor issue? I cant 100% confirm this fault as again 2nd hand information here.

Fingers crossed I'll have some updates this week and she'll finally be back on the road! (has been in storage in my garage on a CTEK... last MOT... May 2019!)

And hopefully these posts might assist someone in the future.
Had a call with the Indy,

Although it hasn't been taken for a proper test drive yet, appears a calibration has cleared the steering angle fault.

I'd read about security code on US forums, in order to have this done I had to supply V5, photo ID and utility bill in order for the indy to get the code from Porsche to be able to perform this.

Also appears one of the tyres now has a nail in, brake lines are corroded and there's a slight coolant weep from somewhere up front.

Getting the first MOT in 2.5 years is proving to be a challenge!

One unknown is still the emissions, at the MOT fail in september they didnt bother to test due to condition of the backboxes (seams and flexis on the PSE were completely shot)

Last MOT I had we struggled to get under 1.03 (with bad condition back boxes) I've had design tek supremacy boxes installed now, but haven't had a chance to hear them yet! Chap at the first garage said they sounded good though. 8)
Calibration was the most obvious and first point to try so good news its a simple fix .

It would be worth recommending to your local garage to buy a Piwis 2 .. they are pretty cheap these days .. they cover cars upto about 2015 and also have wiring diagrams for 997 onwards ..

The cost of this would be probably the time cost they spent on this car so well worth it .. i can supply operating instructions if needed .

Not sure why you needed codes to calibrate this system .. you need them to code on keys , alarm and dme but Not for this job ..

V5 etc is to prove you own the car as the codes are the security numbers for your car to allow keys to be programed on ... i can only assume they have a very early tester as it not required for piwis 2/3 .

Coolant will probably be a rad on these .

Brake lines will probably be n/s and under the undertray .. common area for these to corrode in the brackets .

Split exhaust .. air enters the system and the mot CO tester thinks there is an issue with the car so fails it ... in reality it's a false reading as the engine is running fine .
Eugh... the saga continues

Obviously MOT inspections differ however

MOT fail on 15.09.21

Repair immediately (major defects):
Offside Rear Service brake excessively binding (1.2.1 (f))
Nearside Front Lower Suspension arm ball joint excessively worn (5.3.4 (a) (i))
Offside Front Lower Suspension arm ball joint excessively worn (5.3.4 (a) (i))
Steering system excessively rough (2.1.1 (a))
Exhaust has a major leak of exhaust gases (6.1.2 (a))
Emissions not tested ( (d))
Monitor and repair if necessary (advisories):
Nearside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
Service brake only just met requirements
Handbrake performance only just met requirements

and I've just checked online
Failed today at the MOT centre the indy use on;

Repair immediately (major defects):
All direction indicators not working (4.4.1 (a) (ii))
Hazard warning lamps not fitted (4.4.1 (d))
Hazard warning switch inoperative Missing (4.4.2 (a) (ii))
Nearside Headlamp aim too high (4.1.2 (a))
Offside Rear Position lamp not working (4.2.1 (a) (ii))
Indicator switch inoperative (4.4.2 (a) (ii))
Repair as soon as possible (minor defects):
Offside Registration plate lamp inoperative in the case of multiple lamps or light sources (4.7.1 (b) (i))
Monitor and repair if necessary (advisories):
Nearside Brake pipe corroded, covered in grease or other material front to rear (1.1.11 (c))
Offside Brake pipe corroded, covered in grease or other material front to rear (1.1.11 (c))
Offside Rear Anti-roll bar linkage ball joint has slight play (5.3.4 (a) (i))
Offside Rear Nail in tyre ()
Nearside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))
Offside Rear Tyre worn close to legal limit/worn on edge (5.2.3 (e))

Going to have some fun here! (haven't managed to get through to anyone yet)

...got through to MOT station, the hazard switch had been removed from the car when it was presented for a test, fingers crossed a new one being fitted sorts all of that out

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