P1499 EGR Stepper Motor

Technical Area Electrics & ICE
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  1. My model of MX-5 is: _1.6 NB 2004
  2. I’m based near: __St Albans, Herts
  3. I’m looking for technical help or recommendations on: _Error Code P1499
  4. I have currently an engine management light on with error code P1499
    IMG_0884 2
    IMG_0884 21170×2532 170 KB

    I checked the resistance across the pins / coils of the EGR valve.
    Screenshot 2025-05-01 at 18.32.02
    Screenshot 2025-05-01 at 18.32.02502×598 32.5 KB

    These were the figures
    C-E 22.5
    C-A 22.6
    D-B 23.4
    D-F 0.6
    As D-F was out of tolerance I replaced the EGR valve. I started the car and no EML on. Happy days I thought!
    I went to use the car this morning and the light is back on with the same code?
    I checked the resistance figures on the new valve and they are all in between 20-24.
    I have had a look at the ECU and there does not appear to be any chips burnt or damaged.
    IMG_0890
    IMG_08901920×1506 605 KB

    IMG_0891
    IMG_08911920×1440 484 KB

    I have checked the 17 pin connector on the ECU and the plug and can’t seen any damage.
    Any help or advice would be greatly appreciated.
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It’s not what you want to hear and it’ll probably cause you a world of pain and I know that you can’t see anything but I’d guess that the PCM is fried. The EGR valve has basically gone dead short to ground and taken the PCM with it. If you can find someone to repair it, good on ya, but I suspect that you’ll be into used PCMs, immobiliser units, lock sets and keys.

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I just took mil bulb out , put it back just before mot as it only came on after being driven

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Thanks Robbie I did fear this scenario after seeing another thread, but they saw damage on the ECU. (The storm clouds are gathering :roll_eyes:)
When I get it fixed I will let you know.

1 Like
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I have tried to get the ECU checked and tested with no success. I am now trying to source another ECU, lock set and immobiliser.
My question is what’s to stop the EGR valve doing this again?

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You could put a fuse inline with the 12 volt feeds to the stepper motor to protect the PCM, the theory being that the fuse blows before the PCM. Can’t remember what amperage fuses to use. A search on this forum might find you the answer.

Edit… Seen this?

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Update: I fitted another ECU, supplied by Rob Rhind (rhino666) . Just been out for a fifty mile spin and all seems good. :+1: