N52 330i abs sensor and fluctuating revs

9804942R · 03-15-2017, 11:26 AM

Hello all, new member here.

After a couple of year’s absence from BMW ownership I have yet again joined the club. I used to frequent bmwland but now see that this has sadly ceased.

After a lot of research on here I decided to go for an early e90 n52 330i. I managed to source a very tidy one with low mileage which will hopefully do me well.

I have a couple of issues with my car which hopefully some people on here will be able to give an opinion on.

1) The person I bought the car from informed me that the abs, traction control and parking brake lights came on a couple weeks ago. His scanner identified this as the left rear wheel sensor so he booked the car in for replacement; however the problem disappeared and didn’t return so cancelled his slot at the garage. Of course when I was driving home from one end of the country to another the problem re-appeared but only once travelling at speeds north of 80mph (I also noticed the speedometer slightly fluctuating). The warning lights clear as soon as you stop and restart the car. I am waiting on delivery of the creator c310 scanner but am expecting it to point to the same sensor. In the meantime when I looked in to the problem I understand that it could either be the sensor or reluctor ring. I took the sensor out to see if it was damaged by the ring; it was dirty but wasn’t damaged. I cleaned and replaced it, the speedometer doesn’t fluctuate anymore but the problem is still present.

Does this sound like the sensor is simply on its way out and is struggling at higher speeds? I don’t understand how the sensor would be ok at a low speed but then fail at a higher speed.

Also does anyone know who makes the BMW sensor, the ATE ones are half the price and just wondered if it was the exact same sensor.

2) The rev counter also fluctuates very slightly; I am talking 75 rpm at most. I see and hear no difference in the engine when it does this. Looking into the problem, people usually experience this at idle but this car does it at all speeds and doesn’t seem severe as the people with rough idle problems. No warning lights come on due to this and the car runs absolutely fine.

Does anyone have any idea what would cause this? I was thinking, possibly a sign of an impending coil pack failure maybe? Or could it be just a faulty signal going to the rev counter?

Thanks in advance for any replies.

Thermobaric · 03-16-2017, 02:35 PM

I had this. Fluctuating revs, traction control, ABS lights e.t.c. Error code was even rear left wheel speed sensor too.

I had to replace the reluctor rings and sensors to sort it.

9804942R · 03-16-2017, 05:50 PM

Thanks for the response thermobaric.

I didn't think the revs would be connected to the speed sensor. That is interesting.

I received my scanner and as predicted it pointed to the left rear sensor, so have ordered a replacement, I hopefully don't have to also replace the reluctor ring.

Whilst I was playing with the scanner and the live data stream it did point to a smooth running test on one of the cylinders to be out of the specified parameters. I have a spare coil pack so was going to replace it to see if it improves it. Will do it separately to the wheel sensor though to determine if these 2 faults were connected.

Thanks

Thermobaric · 03-16-2017, 06:25 PM

Yeah. The rev thing was weird. It makes no sense to me. I was planning on sorting it after I did the reluctor rings but it never happened again. The speedo fluctuating makes sense as the scratched up rings were screwing with the sensors. I guess it is just one of those things heh.

Calluhan · 03-18-2017, 05:02 AM

Quote:

Originally Posted by Thermobaric

Yeah. The rev thing was weird. It makes no sense to me. I was planning on sorting it after I did the reluctor rings but it never happened again. The speedo fluctuating makes sense as the scratched up rings were screwing with the sensors. I guess it is just one of those things heh.

I've just had these symptoms. Was it straightforward to replace the reluctor ring? Did you DIY? Grateful for any info. as pulling driveshaft looks straightforward but not sure I can be arsed

this cold weather makes me feel old

Thermobaric · 03-18-2017, 07:17 AM

Nah. I had it done at a garage. I gather it was a pig of a job for my particular car as it took a bit longer than they expected. It depends on the condition of the drive shafts I believe so will vary from car to car.

DIY would save you a lot as parts are pretty cheap. I just really couldn't be arsed. Ended up costing me £430 or so.

9804942R · 03-28-2017, 04:41 PM

Just to update everyone.

I replaced the sensor and this has cured the lights coming on. Revs still fluctuate so must be something different in my case. I will update when I get to the bottom of that.

Oh the BMW sensor is indeed an ATE sensor.

03-15-2017, 11:26 AM	#1
9804942R New Member 1 Rep 8 Posts Drives: e90 330i SE Join Date: Mar 2017 Location: Scotland iTrader: (0)	N52 330i abs sensor and fluctuating revs Hello all, new member here. After a couple of year’s absence from BMW ownership I have yet again joined the club. I used to frequent bmwland but now see that this has sadly ceased. After a lot of research on here I decided to go for an early e90 n52 330i. I managed to source a very tidy one with low mileage which will hopefully do me well. I have a couple of issues with my car which hopefully some people on here will be able to give an opinion on. 1) The person I bought the car from informed me that the abs, traction control and parking brake lights came on a couple weeks ago. His scanner identified this as the left rear wheel sensor so he booked the car in for replacement; however the problem disappeared and didn’t return so cancelled his slot at the garage. Of course when I was driving home from one end of the country to another the problem re-appeared but only once travelling at speeds north of 80mph (I also noticed the speedometer slightly fluctuating). The warning lights clear as soon as you stop and restart the car. I am waiting on delivery of the creator c310 scanner but am expecting it to point to the same sensor. In the meantime when I looked in to the problem I understand that it could either be the sensor or reluctor ring. I took the sensor out to see if it was damaged by the ring; it was dirty but wasn’t damaged. I cleaned and replaced it, the speedometer doesn’t fluctuate anymore but the problem is still present. Does this sound like the sensor is simply on its way out and is struggling at higher speeds? I don’t understand how the sensor would be ok at a low speed but then fail at a higher speed. Also does anyone know who makes the BMW sensor, the ATE ones are half the price and just wondered if it was the exact same sensor. 2) The rev counter also fluctuates very slightly; I am talking 75 rpm at most. I see and hear no difference in the engine when it does this. Looking into the problem, people usually experience this at idle but this car does it at all speeds and doesn’t seem severe as the people with rough idle problems. No warning lights come on due to this and the car runs absolutely fine. Does anyone have any idea what would cause this? I was thinking, possibly a sign of an impending coil pack failure maybe? Or could it be just a faulty signal going to the rev counter? Thanks in advance for any replies.
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03-16-2017, 02:35 PM	#2
Thermobaric Captain 65 Rep 670 Posts Drives: BMW E92 Join Date: May 2015 Location: Bucks iTrader: (1)	I had this. Fluctuating revs, traction control, ABS lights e.t.c. Error code was even rear left wheel speed sensor too. I had to replace the reluctor rings and sensors to sort it.
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03-16-2017, 05:50 PM	#3
9804942R New Member 1 Rep 8 Posts Drives: e90 330i SE Join Date: Mar 2017 Location: Scotland iTrader: (0)	Thanks for the response thermobaric. I didn't think the revs would be connected to the speed sensor. That is interesting. I received my scanner and as predicted it pointed to the left rear sensor, so have ordered a replacement, I hopefully don't have to also replace the reluctor ring. Whilst I was playing with the scanner and the live data stream it did point to a smooth running test on one of the cylinders to be out of the specified parameters. I have a spare coil pack so was going to replace it to see if it improves it. Will do it separately to the wheel sensor though to determine if these 2 faults were connected. Thanks
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03-16-2017, 06:25 PM	#4
Thermobaric Captain 65 Rep 670 Posts Drives: BMW E92 Join Date: May 2015 Location: Bucks iTrader: (1)	Yeah. The rev thing was weird. It makes no sense to me. I was planning on sorting it after I did the reluctor rings but it never happened again. The speedo fluctuating makes sense as the scratched up rings were screwing with the sensors. I guess it is just one of those things heh.
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03-18-2017, 07:17 AM	#6
Thermobaric Captain 65 Rep 670 Posts Drives: BMW E92 Join Date: May 2015 Location: Bucks iTrader: (1)	Nah. I had it done at a garage. I gather it was a pig of a job for my particular car as it took a bit longer than they expected. It depends on the condition of the drive shafts I believe so will vary from car to car. DIY would save you a lot as parts are pretty cheap. I just really couldn't be arsed. Ended up costing me £430 or so.
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03-28-2017, 04:41 PM	#7
9804942R New Member 1 Rep 8 Posts Drives: e90 330i SE Join Date: Mar 2017 Location: Scotland iTrader: (0)	Just to update everyone. I replaced the sensor and this has cured the lights coming on. Revs still fluctuate so must be something different in my case. I will update when I get to the bottom of that. Oh the BMW sensor is indeed an ATE sensor.
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