Spongy breaks

[jbrodin]

Three times now, I’ve had two warning lights come on (see photo) and the breaks feel ‘spongy’ for a while. It sorts itself out if I keep driving, and if I turn off and on the engine, the warning lights don’t come back. I used an ODB scanner, and the only trouble code I got was ‘P0161 O2 Sensor Heater - Circuit Malfunction (Bank 2 Sensor 2). That does not seem to be related to the warning lights. Any ideas would be highly appreciate. Thanks.

 

[colb]

The warning lights you have are brake related, the code for the duff heating circuit in the exhaust sensor will have nothing to do with the braking system. I would have expected that you would have had an EML dash light up for the exhaust sensor to warn of that failing.
As to spongy brake pedal you need to check the brake fluid reservoir and ensure its up to the level, then check all brake lines for signs of leaks. If no leaks found check the vaccum pipe that runs to the brake booster for leaks and condition of the rubber hose.
Finally go around the car and bleed the brakes starting at the farthest from the master cylinder (rear) then other rear then front farthest from the master cylinder and finally the other front caliper. Once you are satisfied all the air has been bled from each and you still have a spongy pedal turn your attention to the master cylinder, internal rubber seals may be failing. If that is the case then replace the unit.

 

[t-tony]

If the brake fluid level appears low check the clutch slave cyl. for leaks too.

Tony.

 

[Stevo7682]

I would plug your diag tool back in and re check the abs.
If the abs and traction control light come on at all even only for a few seconds the corresponding fault code should be placed in the memory the only way to remove the stored code would be to read it then delete it.
So the fact that you have a picture with the lights on there has to be a fault code stored in ecu.
Look at this first before messing around bleeding etc.
As the abs pump itself could be at fault creating the sponginess in the pedal and putting lights on dash .

Stephen.

 

[t-tony]

It would help knowing where you plugged your OBD scanner in. Under the bonnet?, or under the dash?
If you plugged in under the dash it wouldn't have read the brake codes anyway.

Tony.

 

[jbrodin]

It would help knowing where you plugged your OBD scanner in. Under the bonnet?, or under the dash?
If you plugged in under the dash it wouldn't have read the brake codes anyway.

Tony.

Is there a plug under the bonnet, I didn’t know that. Where is that located?

 

[Stevo7682]

Is there a plug under the bonnet, I didn’t know that. Where is that located?

As Tony has said because you used the 16 pin obd under steering column you only really get engine ecu and gearbox ecu ( 5sp auto) access.
Only face-lift models have the 16pin one .
All z3 have a 20 pin round obd port in the engine bay I have a pre face-lift 2.8 and 1.9 and a face-lift 1.9 and all 3 are in different locations so not sure exactly where yours is on the 2.2 but this is what you are looking for

This is the location on the pre face-lift 2.8 tu engine yours will look the same just maybe different place
Then you will need one of these

Which is a 16 to 20 pin obd cable.

Just go on ebay type
16 to 20 pin obd
Should bring up around 300 or so of them ( less than a tenner) .
Buy this first then redo your scan with 20 pin go to abs see what faults are there start from that before you touch anything else .
Then you can come back on here and we'll see if we can help out .

Stephen.

 

[Zephyr]

Is there a plug under the bonnet, I didn’t know that. Where is that located?

edited because @Stevo7682 wrote first.

before buying an adaptor try thus trick if you have a plug inside the car.

This round plug.
you will need an adaptor from round to regular obd2 to read faults, or you can bridge these two pins on the round one and you will have full access to your modules from the square one (inside under the dash).

 

[Stevo7682]

Sorry @Zephyr
Know what it's like when you writing out a big paragraph about something and someone else posts it up just in front of you
I pretty much do everything I do on the forum on my phone so some of the bigger stuff with pictures takes time to do .
Stephen

 

[Nodzed]

edited because @Stevo7682 wrote first.

before buying an adaptor try thus trick if you have a plug inside the car.

This round plug.
you will need an adaptor from round to regular obd2 to read faults, or you can bridge these two pins on the round one and you will have full access to your modules from the square one (inside under the dash).
View attachment 239977

Who knew?

 

[jbrodin]

Thanks guys. I tried the 20 pin under the bonnet now. Still doesn’t show anything related to brakes or ABS. The app I’m using is only showing engine and gearbox fault codes apparently. What do you guys use to see all codes, including ABS?

 

[Stevo7682]

I have a Creator c310+
Also have the cheaper

Someone else will probably be along at some point with other recommended products these are just the ones I have personally used.

Stephen.

 

[Zephyr]

iCarsoft BMM V2 I can see pretty much everything.

 

[Woodsta888]

Foxwell NT 680 All systems, all makes up to 2020, lifetime free updates. Paid for itself reading other peoples codes, tenner a time.

 

[jbrodin]

Bought a Creator C310+ (next day delivery from Amazon). Cheap chinese piece of cr*p, but it does the job.
ABS/ DTC is showing 5DF4 ”System voltage < 9 volts” and 5E24 ”Pressure sensors”
Since the fault is intermittent, I’d assume there is some connector that need to be cleaned.

 

[Stevo7682]

Pressure sensors ( there are 2 of them ) are mounted into the lower section of the brake master cylinder one not too bad to change other slightly more awkward.
They look like an oil pressure switch and are dealer only at around £130 each

Stephen.

 

[colb]

If you don't want to pay Dealer price for the Brake Sensor take a look here on ebay

2× Brake Pressure Sensor Switch For BMW E46 E60 E61 E63 E64 Z3 Z4 OEM34521164458 | eBay

Find many great new & used options and get the best deals for 2× Brake Pressure Sensor Switch For BMW E46 E60 E61 E63 E64 Z3 Z4 OEM34521164458 at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

Fitted one of these to my Z4 when it set a code, always reluctant to use pattern parts but gave these a try and its still working 8 months later only needed 1 so the other is in the parts stash just in case.

 

[jbrodin]

Thanks for all tips. I have located the sensors. It’s extremely tight to reach them.

 

[t-tony]

As a mechanic being very flexible or double jointed can certainly be a help.

Tony.

 

[Stevo7682]

As a mechanic being very flexible or double jointed can certainly be a help.

Tony.

Totally Tony.
I have done these sensors on @Iain C zed access is tight biggest problem was the hex on the sensor is around 27mm.
So the issue was getting something in that would fit round it ( spanner ,shifter) but still fit in the space I ended up undoing a number of the bolts on the panel that separates the brake master etc from the engine bay to get to it rear one was the issue access right awkward it's only the initial cracking loose and the nipping back up that the issue not tight on threads screw in and out by hand.
Stephen.