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Car won't start after battery out for extended time

RCZ-mad

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Hey thanks for the photo. That location is right in the area where I had been moving things around. I had completely removed the airbox, and taken the nuts off to remove the intake manifold (but just so I could move it into any position, I didn't completely unhook everything and take it out).

But the vacuum reservoir that is right next to the oil gauge sensor, I had removed the nuts securing that so I could move it to the side and allow me to secure the flexible hose to the coolant crossover pipe.

Since I was moving that around, I think its possible it damaged the wires coming out of the top of the oil gauge sensor.

So I think the F40A error mentioning the oil gauge sensor is because it simply isn't receiving any signal from it, so its as if it thinks the sensor isn't even there, which would explain why it won't let you clear the code.

Obviously now I need to check the sensor connector, but considering the location, I would have to take everything off that I had to when changing that crossover pipe, and that is so much hassle that I really want to avoid that.

I've checked the workshop manual and it mentions to change that sensor, you simply remove the bottom engine protection tray and get it on a hoist, then from that raised position you can get to it from underneath instead, has anyone changed one of those sensors before? Its very cramped back there, how easy is it to access it when hoisted up? Would you have clear line of sight to see if the connector is still on or the wires running to it are damaged?
 

EddieJ

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It can be got at reasonably okay, and seen, from underneath on drive on ramps, lift much nicer. Tray off and the awkward thing is that the driveshaft support bearing is right at it.
If trying to remove it, it then can be a pig, it’s maybe 6/7” long and as you already know there isn’t much room above, vac solenoid etc. Maybe plug just needs a wiggle back in place. If you have had oil leaks from say the rocker cover gasket running down the oil can have caused the wires to bake brittle so tread with care moving wires. When you first start your car do you get the Oil Ok message? If you do chances are it is actually okay and just blip on the scan. Example on one of my cars if I scan faults say 3 times there are no faults, then on fourth that code is there, then not the next. Always reads oil okay on dash at start and no on dash lights. Because I dip mine every week or two never really that concerned about it.
 

EddieJ

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just nipped out and took my sump off to be sure 😜(old pics from timing chain job), the oil sensor, black rod seen coming through the edge of the block

1765021908278.jpeg
 

RCZ-mad

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It can be got at reasonably okay, and seen, from underneath on drive on ramps, lift much nicer. Tray off and the awkward thing is that the driveshaft support bearing is right at it.
If trying to remove it, it then can be a pig, it’s maybe 6/7” long and as you already know there isn’t much room above, vac solenoid etc. Maybe plug just needs a wiggle back in place. If you have had oil leaks from say the rocker cover gasket running down the oil can have caused the wires to bake brittle so tread with care moving wires. When you first start your car do you get the Oil Ok message? If you do chances are it is actually okay and just blip on the scan. Example on one of my cars if I scan faults say 3 times there are no faults, then on fourth that code is there, then not the next. Always reads oil okay on dash at start and no on dash lights. Because I dip mine every week or two never really that concerned about it.
That's a good pic thanks, I'll be able to find it much quicker when I get under there!

The oil level is correct (dipstick confirmed) and when I start the car, the first message I get is: "Oil level correct"

Then that is immediately followed by: "Engine fault: Repair needed"

So I'm willing to bet I've damaged the wiring in some way. I'll get it hoisted soon at a place I know and see what I find, (not willing to get under there and do this on jack stands).

If the wiring is broken or even yanked out of the connecter head, I'll try to do the wiring repair where it is.
 

RCZ-mad

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Ok I managed to get it up on a hoist for a quick check of the oil level sensor and as far as visual inspection goes, the connector is on solid and the wires going to it seem to be connected, can't see any damage to them from this angle.

Thinking about it though, if the wires themselves were damaged causing loss of proper signal, or if the sensor itself was faulty, then surely that means I wouldn't see the message 'Oil level is correct' when starting the car?

Surely if that sensor was not working, then I wouldn't get that message and I would only see a CEL?

Its confusing, because after getting all error codes cleared, the 040A is the ONLY one that cannot be cleared, at least by the garage that checked it, and its apparently the oil level sensor. I've also seen suggestions of doing a BSI reset procedure, but did that and no good.

So how can I get a message telling me the oil level is correct if there is supposed to be a fault with the sensor?

I wonder if there is another related sensor or system that is combined with the oil level sensor that is perhaps the real issue, and the fault code is simply a more generic code.

What I mean is, I replaced the thermostat housing, and from what I've read in multiple places, there is some kind of interplay between the oil sensor and the coolant sensor. Driving the car around, the coolant temp has never been an issue since doing the change, the engine warms up and coolant temp has never wavered or inched higher than ideal, so it appears the thermostat is fully functioning. And the coolant sensor itself is the original one, I didn't replace that, and it was fully functioning before I changed the thermostat.

So this is a mystery, but I think I can safely rule out sensor faults, because this issue only arose after I did the work, therefore most certainly this issue is due to something I've done, or not done (as in, perhaps I forgot to plugin a sensor at the back?).

Anyone got any other ideas?
 
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