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2010 Diesel 451 with seemingly incurable safe mode problem

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  • 2010 Diesel 451 with seemingly incurable safe mode problem

    Hi all

    For the last 9+ months my 2010-plate Diesel 451 has had a seemingly incurable tendency to enter a type of safe mode which seems to be utterly undetectable by the diagnostic equipment at the Smart Car Specialist in Guildford. Here are some details, when the car enters safe mode:
    • The engine cannot rev above 3,000rpm
    • The car feels much more sluggish and will struggle to climb any type of gradient. You also cannot accelerate hard because of the rev limiter
    • The Engine Warning Light doesn't illuminate
    • It's possible to fix the problem by switching the engine off and on again. Originally I had to pull to the side of the road to do this, but I've found the engine can be switched off and restarted whilst coasting in neutral. The car then drives absolutely fine as if nothing had happened.
    No errors are logged / stored in the OBD system and hence no errors come up when the car is connected to a diagnostic machine.

    When driving normally the car feels absolutely fine, has plenty of power, the turbo spools up fine and gives the kick one would expect after ~2250rpm, etc. The garage also did a compression check and said it was fine. They did say the battery seems to be dropping voltage quite quickly, not sure if that could be anything to do with it ...

    I've not been able to find any common situations / circumstances which cause the car to enter the safe mode. Between about February and early July this year it only entered safe mode twice, then on a very typical journey in mid July it did it 5 times on one day, AND the Engine Warning light then illuminated! On taking it back to SCS, they said no errors were logged in the system and they don't know what caused the light to illuminate

    As you can imagine this has become extremely frustrating. My wife no longer wants to drive the car, the garage don't know what's causing the problem, and I wouldn't feel happy to sell the car privately knowing that it has this problem. It's a shame as cars of this age seem to sell for around 3,000 on AutoTrader. values the car at 1645, but that's before I've told them that it has an intermittent safe mode problem which is likely to reduce the amount they'd be prepared to pay.

    So what do I do? Sell it through and just accept what they give me? Start spending money replacing bits which the garage think may be the cause (faulty sensors in the exhaust have been suggested as a possible source of the problem, particularly given the intermittency of the problem)? ...

    Many thanks for any thoughts or ideas you would like to share, it's much appreciated.


  • #2
    I will pay you 1500 to buy it as I know how to fix it

    020 328 REMAP (02032873627)
    STAR diagnostics. Remapping. Dyno. Key coding
    TAN codes. SCN codes. Body shop. Trimming. Crash repairs


    • #3
      Thanks for buying the car off me Ian, it was a pleasure doing business with you So glad to hear you were able to fix the problem too! Would you be happy to share the results here for anyone else who experiences this problem in the future?

      Thanks again and happy smarting!


      PS. The sale of this car leaves us smart-less, but we're now the very happy owners of two electric cars, a Kia Soul (to be replaced by a Hyundai Ioniq next month) and a Renault Zoe which has directly replaced the Smart and is now my wife's commuting car


      • knoxville2k
        knoxville2k commented
        Editing a comment
        Can you share with us the issue?

      • Hogster
        Hogster commented
        Editing a comment
        Unfortunately I don't know the exact cause of the issue – Ian didn't really go into details when I asked him. I think it was something software related though if I remember correctly.

    • #4
      I have exactly this issue other than I get a pending fault code of p0299.
      Amy help here would be great! Please?


      • #5
        I experienced a similar issue as my car turned 70000 miles, the dealership couldn't find a fault as no fault code came up, they replaced the DPF (diesel particulate filter), problem solved, the car turned 102000 miles earlier and hasn't missed a beat


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