Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)

Recommended Posts

Hello !! I have a mystery I need help with. My car is a 2001 996 Turbo manual.

I drove my car for 30 minutes, parked it and went on an appointment. Returned an hour later and...it would not start and ended up with a tow truck recovery. Well, having followed all the good advise on reasons and cures for non starting - my car still wont start !! New fuel pump relay, new fuel pump, new battery and new fuses. There is over half a tank of fuel and plenty of battery power. Itturns over really well but it will not fire !! Any other thoughts or potential reasons that I may have overlooked ??

best wishes


Link to post
Share on other sites
    You can remove these ads by becoming a Contributing Member.


Try bypassing the clutch interlock switch by installing a temporary jumper wire at the switch. You will find the switch directly behind the metal arm of the clutch pedal.

Regards, Maurice.

Link to post
Share on other sites

Have you scanned it for codes to make sure the ECU is still working?

Also check to see if the throttle body (TB) is operating, turn the key on and let it sit, go back by the engine bay and you should hear a whine and a few ticks as the throttle body runs through a cycle and does a reset, usually takes a minute for it to start after you turn the key on. If you dont hear this, the TB may be bad and could be fully closed not allowing enough air in for the car to start.

You did fuel pump, did you change the fuel filter?

Plus the clutch switch as mentioned already.

Link to post
Share on other sites
  • 2 weeks later...

If you feel under the drivers seat do you feel any moisture? Sounds to me that it could be an immobilizer issue. If you have a way to check for fault codes with a tool that can read factory codes, you may have see an immobilizer fault in the DME. This would mean that it is not communicating with the Alarm module. Other possible immobilizer faults may be stored in the Alarm module. One quick check you can make with any scan tool is to see if you can connect to the engine module. You can do this even with an OBD2 tool. While the OBD2 tool will not tell you the immobilizer faults, nor will it read the alarm module. But if you can connect via these tools it will tell you that the K-Line connection between the alarm module and the DME is working. If you are unable to connect, then this would show that there could be a problem with the Alarm box. The communications used by all scan tools to the engine is routed from the OBD2 port first to the Alarm module then from the Alarm module to the DME. This same wire that is used for diagnostic tools is also used by immobilizer system to exchange codes prior to authorizing startup.

Link to post
Share on other sites

Thanx for all the help and apologies for the delay in replying - mad time of year.

Problem sorted - it was the fuel pump but also a faulty new relay, so put "old" one back and it fired up. Car currently with PARR for extensive changes and will post after completion sometime in late January.

best wishes


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Content

    • By Riley98697
      This week I have been struggling with a intermittent starting issue on my 1997 boxster 5 speed. I replaced the ignition switch battery and clutch switch in hopes that it was something easy. With no effect on my part I decided to let my local dealer fuss with it. $200 later my problem has been diagnosed as the dreaded immobilizer being wet. I. Got a quote of $3600 parts and labor to remedy the problem and it seems foolish to put over half the cars value into repairs. My quest for posting today is to look for more wallet friendly ways of repairing or replacing the immobilizer. 
      I will buy a waterproof cpu case and look into roof leaks while the unit is out. 

    • By Wolfsrun
      Good afternoon all,
      This is my first post but want to start by thanking all who have shared there knowledge on other posts as it has allowed me to fix various items on my car.
      looking for assistance before i take the car to the dealer. i think it is down to the mobilizer but not sure if there is something easy i am over looking.
      currently have a no start / no crank condition. when i pulled the car out of winter storage it would crank slow but not start.
      1) Replaced the battery, still no start. Then turned into no crank.
      2) Replaced ignition switch, started and ran for 10 -15 minutes; but would not restart.
      3) Have 12V to pin 30 of the starter relay when key turned to start. And if i short pin 85 (from DME) to ground it cranks but wont start.
      4) Replaced Starter relay with a new one. Will "click" when key turned but not hold.
      5) swapped the DME relay with another one. (read a post somewhere that this fixed a similar issue for someone)
      6) bypassed clutch switch
      7) very occasionally (1 out of 40 to 50 tries) car will fire up. this may coincide with having the battery disconnected for 30+ min first but is not guaranteed.
      ? removed the control unit under the seat and when open appears to be in good condition, no moisture / corrosion. 15 amp fuse confirmed good.
      9) checked all fuses in driver foot well, no issues found.
      have tried both keys with the same results.
      At this point i think either the immobilizer or ECU are the problem but do not have an appropriate scan tool for either of these.
      can any of you recommend something i should try before going to the dealer?
    • By Stephen Semenchuk
      Looking for suggestions. I replaced both fuel pumps of my 2005 Cayenne Turbo after the main pump died. Got it all connected back up and she runs great.... until it gets down to a bit under a quarter tank. Sometimes the engine just quits, other times the throttle gets intermittently rough, it shudders however, if I feather the gas lightly, it will continue to drive, if I press harder on the gas, it stalls. When I pull over and restart it, it drives fine for about a mile or so then same thing. Has anyone experienced this after replacing the fuel pumps? Is there an installation “gotcha” that I missed? Thanks in advance for all your expert opinions.
    • By Loscano
      I purchased a 1999 Porsche Boxster 986 about a year ago and I'm having a few problems with the electrical accessories.  The top worked fine when I bought it, but now it won't work sometimes. The radio also turns on, then immediately off at startup, and it won' turn back on until a few minutes later either by itself, when I use turn signals, power windows, brake, or even just by itself. After the car is "warmed up", then it will stay on. Other things won't work right or not at all, such as the alarms for, ignition, door open, light switches, etc. The fuses are all fine, and I know the battery had been replaced right before I purchased it. I haven't checked the relay for the top, but I am about to do that now. I feel like there could be a single problem creating all these issues. Any help would be greatly helpful and appreciated! 
    • By Travisb
      Greetings and thank you for the informative site.
      I am a new owner of a 2009 Cayenne base model with dead Horn.  I’ve read on the forum of typical failures, including steering wheel wire and two horn units. So far I’ve confirmed the fuse is ok.
      Before removing wheel arch covers to test the horns, I wanted to check the relay.
      Is the horn relay in the under hood fuse box? If so, which position?
      thank you,
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.