jonnyrocka

Good morning all,

I changed my brake pads and alternator last weekend when I went to start car up once I was done I had an engine management light come up I have checked the code is po558 brake booster pressure sensor high.

The car drives fine I have tryed to clear the code but it keeps coming up any ideas on how to fix?

Cheers jon

Bob Rawle

Means the sensor is probably open circuit, so maybe you dislodged the connecting wire(s) when doing the changes ?

best regards

bob

jonnyrocka

I do hope its something that simple well im getting the sway bar links replaced on sat so will have a look and give them a clean

l70byb.

iTrader: (5)

Any idea where this sensor is fitted on a new age car? As I friend of mine has the same problem

jonnyrocka

Still having problems with this fault and no one seems to have any idea how to fix this. Anyone had this fault as need to get this sorted before the mot.

Current things I have done
Changed altornator
Bleeded the brakes

Any help would be great

sean whiffin

iTrader: (2)

strange as you said you changed the alternator ....i changed an alternator on my brother's 2003 forester xt and he had the same fault code come up (P0558) brake booster pressure sensor high ....we cleared the code but it just comes back up straight away ! Any ideas anyone ?

quango2k

digging up an old thread here but the reason you have a P0558 code after changing the alternator is you have fitted the wrong one.

classics have a three pin connector but not all three are used, some alternators have no pin, others have the pin but it does nothing.

Newage alternators have three pins and all are used..the third is for smart charge. If you have a car that needs the third pin and fit one with a 2 pin...you get the engine light and PO558.

The hard bit is this...both alts look the same physically. if you buy one from a motor factors..they probably dont know there are different types.

you can use a 3 pin on a classic...but not the other way around.

they also output at different level of AMPS.

strausser1

hi i know this is in response to an old post . however i have recently experienced the same problem after mechanic installed brand new alternator on my 2003 forester XT 2.0 New PO558 code and alternator giving only 12.6 -13.0 amps with car running and driving. was unclear regarding your comment on classics vs new age cars
does my 2003 forester require the third pin to be active or does it need only two active pins?

thank for your help (or anyone else that might see this )

Don Clark

A 2003 Forester XT is "classified" as Newage as it should have a smart charge alternator (3 pin).