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1.2 SXi wont start but runs well. Please help! Codes inside...

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  • [Corsa C 2000-2006] 1.2 SXi wont start but runs well. Please help! Codes inside...

    hi all,

    I have jst bought a corsa. I am currently experiencing some difficulty. Sometimes it fires up as normal. Sometimes it struggles into life.

    Tonight it gave up and wouldn't start but I think the next time it may start. When it gets going it seems to run ok, its just with the starting.

    I have done the pedal test. The codes shown are:

    P0300 - Msfire detected
    P0301 - Misfire on cyl 1 detected
    P0303 - Misfire on cyl 2 detected

    I was wondering what this could be. The previous owner said they checked the battery, alternator and spark plugs and then gave up.

    I hav a family member with a corsa design with the same engine. Wondered if it was worth try any parts off it on mine, if so, what? Coil pack?

    Any help or previous experience on my issue would be greatly appreciated. Running my astra H just now but I want to get modding my little c...

    EDIT: should have said, its a 2005 Corsa C, SXi 1.2 petrol, with genuine 48k miles and a 10month mot without a single advisory when it passed 2 months ago... Its too good to be ruined surely?...

    Thanks, Kev.

  • #2
    Trying another good and tested coil pack would be a good start.


    • #3
      Yeah, cant until the weekend. Will test it as soon as I get my grubby mitts on it, but it was just to see if my issue sounded like a c/p issue or not.


      • #4
        Symptoms sound like a crank sensor fault


        • #5
          is that a tough job to fix?


          • #6
            A faulty crankshaft sensor means they usually won't start. It cuts the fuel supply off. Easy way to check - turn the ignition on but don't crank the engine, the ECU should run the fuel pump for a couple of seconds to prime the fuel system. Look at the fuel rail and find the black plastic cap on it, remove the cap and there's a valve inside. Press that and fuel ought to spray out (so be careful!). If fuel is present then it shows that the fuel relay and pump are OK.

            Then crank the engine. If it doesn't fire repeat the test on the fuel rail valve. Fuel pressure should be present. If so it shows the crankshaft sensor is telling the ECU that the engine is turning. If not then it may be a crankshaft sensor failure.

            From the symptoms it sounds like something else - since it seems to be starting albeit not very well.

            The usual route when a misfire is detected is spark plugs - renew them. (Unless you know for 100% sure the previous owner put new plugs in. Old plugs can look OK but cause issues. I had a Yaris in yesterday which kept breaking down, plugs looked fine, but a new set fixed it.)

            Try a different coilpack - great if you've got access to a spare one.

            Then swap the injectors round - see if the misfire follows the injectors, if it does then it's an injector issue. If not then it's something do with the cylinders themselves or possibly the LT feed to the coilpack. P0303 is cylinder 3, not 2. So you've got 1 & 3 both misfiring, ie the two that are linked in the firing sequence. So check if after swapping plugs, coil and injectors the same two show the misfire. Hopefully not, it's usually something more simple.
            1972 Viva restoration thread -


            • #7
              Thanks for all the reply.

              And a special thanks to you Taurus for that lengthy and detail reply. Know that it is much appreciated and has given me a very good method of ruling things out that were the suspected cause, but without replacing them i didnt know how to check.

              I will go about doing this step by step until i have ruled all of the above out but thanks for that. Will post the diagnosis on the weekend to see how i get on.


              • #8
                I should have also said, I've known these throw random misfire codes when the EGR is sticking, without any sign of an EGR code. Not often, but it's happened a few times. Just something to bear in mind. The way to check it is to clear the codes, disconnect the EGR, then try it. You'll get the EML on and an EGR code because it's disconnected, but so long as the EGR resets to its closed position and isn't permanently stuck then it can solve the misfire on a temporary basis. If the EGR is stuck open you will get starting problems.
                1972 Viva restoration thread -


                • #9
                  I will try that too, infact i may try that tonight. I dont have a haynes manual so i have no idea where to find the fuel rail or this valve... I have had 3 corsa Cs but never had major mechanical issues like this with them..

                  Something that is worrying me now though... My oil is the correct consistency but it is the colour of chocolate.

                  The car was running yesterday and i didnt notice any white smoke or anything. So i dont know. Im just praying that its not a sign of something more serious.

                  I have access to a tech 2 reader. Is it worth getting or will it just give me the same codes? As the only ones the ecu gave are the ones quoted above. Or might it go in more depth?

                  The only thing i find strange, is that since ive had it the EML has remained off. When the ignition goes on, it lights up so the bulb works, but it never came on yesterday to indicate a problem and even now when trying to start it, nothing came up.


                  • #10
                    Look at the pedal test in the tutorial section on here - you can check for fault codes without a reader.

                    If the oil is showing signs of emulsion - a small amount is usual on them, but a lot, especially if showing on the dipstick, can be either the HG, or more usually the timing cover gasket behind the water pump, the seal goes and coolant gets into the oil. Keep a close eye on the coolant level and the oil level. If the coolant goes down and the oil goes up there's your problem. People often assume it's the HG that's gone and flog the car.
                    1972 Viva restoration thread -