2000 911 Unreliable starts - Ignition or Immobilizer

Hello All, I purchased my 996 last summer and there had been an issue with sometimes the ignition doesn't turn the engine over. I have it at the shop getting some Transmission work done and asked him to replace the ignition switch as well. He said the ignition switch isn�t the issue, its an immobilizer box, i called Porsche and they said that�s usually a pass fail not a works 70% not 30% and i can turn the wheel sometimes also helps .. its odd any ideas should i ask him to replace ignition switch regardless? Thanks everyone, Nick

If the immobilizer is preventing the engine from starting there will be fault codes stored. Have the mechanic read out the fault codes and see if "Immobilizer Denied Start" shows up.

Thanks will do!!

How about the clutch pedal switch? What do you mean when you say you can turn the steering wheel and that makes it work? Maybe the steering wheel lock mechanism is stuck.or binding.

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I wondered about the clutch pedal switch, so i try to engage deeply that could be ? Not sure again its odd but sometimes when it doesn't start on the first turn seems like if I turn the wheel it will connect ..? This doesn�t always work so may just be a coincidence.

If it turns over but does not start it could be the crankshaft sensor going bad. If this sensor does not show movement then the fuel pump won't deliver fuel. This can be intermittent. Yo can change this sensor with he engine/transmission in place but sometimes it is corroded in the bell housing for the clutch and then it is much easier to replace with the transmission out of the car. I know this because I had one fail years ago and could not remove it with the transmission in the car as I literally had to pound it out from the inside of the bell housing. And now as I am refreshing the engine and have the engine/tramssion out of the car I decided to replace it and again it was corroded and stuck in the hole and I destroyed it getting it out. This time I am going to clean up the hole and use lots of anti-seize. .

There is a "signal transducer" box about 1.5x2" that mounts on the steering column and an "antenna" (plastic ring around the key hole) that picks up the RFID signal from the key and sends to the signal transducer. I have seen loose connectors or bad connections on these cause this issue. Sounds like it could be your issue..

Just stopped by the mechanic he thinks it is the box said there an intermittent fault code.

The Mechanic thinks its the box said he cleared the intermittent error after getting it to act up then it started .. 🤔 not sure thats the issue though as Porsche said its normally a pass fail. Thanks for suggestions I�ll run them by the mechanic

Issue would get better and worse as time continued i have replaced everything related to starting electric and fuel except these pulled and sending to ecu doc .. the immobilizer definitely had been tampering at some point i had it checked out last year porsche Tech said it was fine no signs of damage .. but the box itself had no sticker .. and this unit doesn�t have the antenna wire and i see a capped wire in harness..

It has been at a mechanics for a while as the issue has gotten worse, ecu immobilizer to ecu repair got a new one mechanic wants it to go back �. Starting to think it must be cam sensor, i haven't checked the other issue in the ignition rfid but that is on list also of the car does not start after the immobilizer is back again for a third time.. spark plug, wires, coils, o2 sensors, ignition switch, new key pill, fuel pump, fuel filter, fuel sensor .. immobilizer ..clutch switch has been tested also. 🤷🏼‍♂️👨🏼‍🔧 fml just want to drive again.. about to sell and buy a cayman lol

The motor simply doesn�t turn now, it went from intermittent to no turn 😒

Confirm whether the starter is functional.

Blue cap is most likely a splice/joint of wires from factory, I.e. not tampered with. It looks too nice to be a hack job. Engine will start without cam sensor signal. It might only throw a check engine light. Do you hear the starter solenoid's typical 'klack',when you turn the key to start? It is just before the starter motor would normally start spinning. You amd/or your mechanic are jumping from one suspected part to the next without (it seems) knowing what the interaction between parts is exactly. That makes it expensive and it takes forever. Your choice, of course but if you come here for advice, then 1. Follow it and report back if anything changed in the failure pattern. 2. Tell us if you don't want to follow it, so we can keep track. -Have you had the ignition switch replaced? If not, do so first. It is known to be causing what you experience. -Bridge the clutch switch by connecting the two wires in order to exclude it causing your troubles. Drive it like that for a while to observe and confirm your switch is the (or at least one of the) cause(s). -Follow Porschetech3's advice. Further hints can be found here https://rennlist.com/forums/996-forum/1349967-sensors-that-can-cause-turn-over-but-no-start.html?ispreloading=1

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Did you ever do what PT3 suggested and check the RFID transducer box connections on the column, and the antenna ring around the ign key hole connection...?

The "motor" sound from the engine bay is the Secondary Air Injection (SAI) pump. You will have to troubleshoot the entire 12V system from the battery to the starter motor. Do you have a solid 12V at the jump point in the engine bay? Have you replaced the electrical portion of the ignition switch? Have you any error codes or CEL? Consider it might be fuel pump related as well. Needs a lot of troubleshooting. Hope you are good with a multimeter. Good luck...

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Let me get this straight. You started the car, pulled it out of the garage on the same day, came back later in the day to drive it back in the garage. It would crank, but wouldn't start and so you had the bright idea of replacing the DME? Wild guess, this is cabriolet. Did it happen to rain when it was sitting outside?