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Help On PASM and Air Con Failing :(

charliefunkuk

Member
Joined
19 Feb 2017
Messages
6
Hello, any advice on below would be greatly appreciated. Here is the story of what happened to my car a 997 C4S cab manual. 2007

Car went in to local garage (non-OPC) due to an engine management light, and running lumpy at low revs. After investigating and putting it on a diagnostic, it was decided that the O2 sensors were the issue.

Due to them all being massively corroded and while the car was in and up on the lift, I had both the pre-cat and post-cat sensors changed for original Bosch ones on both sides of the car. That's four in total! This corrected my original fault completely. All happy there.

There was also an annoying buzzing sound in the cab when driving that I asked them to investigate. It was found some of the bearings in the alternator rollers were making the noise, so I also had changed the Alternator Overrunning Pulley, Alternator Drive Belt, Alternator Tensioning Idler Roller and both the Alternator Deflection Rollers. Again all fixed fine and seem to cure the buzzing sound. All Happy again!

The fault codes while in the garage also showed a fault with the Air Con (this fault was not present when they received the car and faults were first scanned, it only appeared at the end after they had done the O2 sensors. Coincidence??). They advised me that they think the air con system probably needed re-gassing, even though the air-con was working fine the day before in my car. I also noticed the air con radiator fans at the front of the car now come on full pelt from start-up, again they never did before!! Jeez they are nosiy!

I had the aircon re-gassed today at a different place, and the fault is still there and it appears the aircon pump is not coming on, so I have no aircon either, despite it working fine before I put it in the garage for the O2 sensor problem!

10 mins after driving it away from the garage 'PASM INDICATOR FAULTY" appeared on the display. The car was also stuck in sports mode, so it is now a really hard, bumpy ride as I cannot switch it off and there is no response to the switch on the dash. The light on the switch does not even illuminate. I did read up on that online and it said when there is a PASM problem, the car defaults to Sports Mode, which it seemingly has. Awful ride!!

Below is a list of fault codes that were present when they first received the car from me.

P0050 - HO2S Heater Control Circuit, Bank 2 Sensor 1 No Signal
P0154 - O2 Sensor Ciruit No Activity Detected, Bank 2 Sensor 1 No Signal
P0300 - Random/Multiple Misfire Detected Exceeds Limit Value
P0303 - Misfire Cylinder 3 Exceeds Limit Value
P0304 - Misfire Cylinder 4 Exceeds Limit Value

When I left the garage then came back, there were a total of 17 faults left in the system! (TOO MANY TO LIST), including the PASM fault, aircon faults etc etc. You could clear them, but they re-appeared upon restarting the engine. Some took a short drive to appear.

It seems to me the garage may have done something to properly screw up the electrics somewhere!

Anyone got any ideas where I can start to look, especially to get this PASM working so I can get it out of sports mode :(

Thanks in advance.

Neil
 
I would really like to see the fault codes for what faults you have now as that will point to the problems , if you can photo the report of the codes and post perhaps ? or if needed ill pm you an email addy you can send them to.


Edit ..

The reason being the codes that come back are the actual faults on your car and whilst i can guess theres not a lot of point in that as the actual codes will tell me the faults and i can then sumorise .
 
Hello Demort,

Thank you for replying. Ill have to go back to garage as I dont have the new faults written down, but there were heaps. None of
My original ones though. Its a friend who owns the garage so haveto see if i can get him to hook it up again.

My only 2 noticeable issues now are AC failing even though regassed abd this PASM INDICATOR FAULTY. This keeps it in sport mode all time. Im at a loss what to do and OPC gona cost a kings ransom! :)

I took battery off for an hour earlier to reset everything but faults appeared again when I reconnected. :(

Neil
 
Removing/disconnecting/flattening the battery on a 997 can cause all sorts of problems with the various electronics modules, particularly the PSM, PASM and ABS, these usually clear themselves after a short drive.
I wonder what the "diagnostic computer" was and if it has caused some options to be lost as can happen requiring a handover reset to be performed to get them back :nooo:

My headlight washers on the 987.1 stopped working after a flat battery and so require a handover reset to be done next time she`s in for service :sad:
 
Codes

ok so I got my friend to do a new code scan for me today. Still having all the same issues as above. Its been driven for at least 50miles so its defo not going to clear itself for sure.

So let me run down the list of issues from the start and the scans:-

When I first took car in

ENGINE MAN - P0050 - HO2S HEATER CONTROL CIRCUIT, BANK 2 SENSOR 1 NO SIGNAL
ENGINE MAN - P0154 - O2 SENSOR CIRCUIT NO ACTIVITY DETECTED, BANK 2 SENSOR 1 NO SIGNAL
ENGINE MAN - P1632 - A/C REGULATION FAULT EXCEEDS LIMIT VALUE

WE THEN FITTED THE 4 NEW SENSORS TO THE CAR, THIS INVOLVED REMOVING THE CATS AS THE PRE AND POST CAT SENSORS WERE CHANGED (4)

Scan after fitting O2 Sensors

NGINE MAN - P1632 - A/C REGULATION EXCEEDS LIMIT VALUE
AIR CON - 8033 - PRESSURE SENSOR

I THEN TOOK THE CAR AWAY FROM GARAGE AND STARTED TO DRIVE IT HOME, THE "PASM INDICATOR FAULTY" CAME UP ON THE DISPLAY SO I DROVE STRAIGHT BACK TO THE GARAGE. WE SCANNED THE CAR AGAIN.

SCAN AFTER RETURN TO GARAGE

ABS - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
AIRBAG - C152 - COMMUNICATION PSM CONTROL UNIT (DRIVE)
AIRBAG - C158 - COMMUNICATIONGATEWAY CONTROL UNIT (CAN DRIVE)
AIR CON - 8033 - PRESSURE SENSOR
GATEWAY - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
INSTRUMENT PANEL - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
REAR END ELECTRONICS - 8001 - TERMINAL 30 VOLTAGE SUPPLY UNDER VOLTAGE
REAR END ELECTRONICS - 8061 - SIREN COMMUNICATION
PORSCHE ACTIVE SAFE - 8004 - TERMINAL 50 BELOW LIMIT VALUE
ENGINE MAN - P1632 - A/C REGULATION FAULT EXCEEDS LIMIT VALUE


I HAVE JUST BEEN BACK TO THE GARAGE AND HE HAS DONE A RESET AGAIN AND RESCANNED THE CAR AND WE NOW HAVE THE FOLLOWING FAULTS (BEFORE A DRIVE)

ABS - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
AIR CON - 8033 - PRESSURE SENSOR
GATEWAY - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
INSTRUMENT PANEL - C156 - COMMUNICATION PASM CONTROL UNIT (DRIVE)
ENGINE MANAGEMENT - P1632 - A/C REGULATION FAUL EXCEEDS LIMIT VALUE



Any ideas anyone ? :)
 
So despite my local garage telling me that he had checked fuses, I decided to check every fuse in the fuse box one by one! And guess what............a fuse was gone!! Changed it and now EVERYTHING works as it should! What a mess one blown fuse can make! I am so glad as thought that was going to cost me dearly and have to put it into an OPC.

Thanks for comments guys! :)
 
That's a result! What fuse was it?
 
Huge sigh of relief for you.

Glad it was an easy and cheap fix and good to know for all us other forum members.
 
Ypu must be feeling mightily relieved :cloud9:
 
You fixed it before i could get involved .. dam shame i was looking forward to this one :p

Nice going young man ..

On the off chance this happens again .. it may well be the a/c pressure sensor thats faulty .. i have seen this blow the fuse before and yes the fans run flat out .
 

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