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A week ago, while I was driving my Ford Focus CC from 2008, the check engine light went on. I stopped the car and, having a cheap OBD-II diagnostic tool with me, I looked over the errors and the car reported:

P2566 Turbo Boost Control Position Sensor Circuit Intermittent

I cleared the error but a few hours later it went back on. I went to a car service and they told me the turbocharger is about to die so I have to recondition it. Meanwhile some lights on the dashboard started to act weird, like the snow symbol turning on along with the seatbelt warning light (but dimmer) and the cruise control light turning on along with the headlights indicator (see video here).

I guess I'm having an electrical issue - I scheduled an appointment to a specialist for the next week, until then is there something I could check on? Could the P2566 error code be related to the other symptoms, or that is a different issue with the turbocharger? Should I disconnect the battery until I take the car to the service?

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To me it sounds like you have electrical issues with your ECU, either because of water damage (and following oxidation) or because of damage to a wire harness. It is a good idea to have an appointment with a specialist because these issues usually are very vehicle specific and general service stations are usually not very well equipped for extensive troubleshooting and diagnostics.

The P2566 error only tells that the ECU is having trouble reading the position of the turbo boost controller, the statement that the entire turbocharger needs to be reconditioned sounds like wild speculation to me. Also see this article about the P2566 issue.

As i stated earlier it is likely that the errors are caused by an unrelated electrical issue. There is no need to disconnect the battery, but it might be wise to keep your car out of the rain until your appointment with the specialist, just to prevent more damage in case the problems are caused by rain water seepage.

  • Thank you for your answer! Do you have any idea where the ECU is usually placed on cars? There were some heavy rain some weeks ago and I drove with my car through a flooded area (the water wasn't very deep but still deep enough to reach the bottom of the bumper) so I'm wondering if the water could reach the control unit. Anyway, this car is not too water-friendly, I often have to clean the rear lamp sockets because of water leaks so it's likely that the erratic behaviour of my car is caused by water damage. – ov1d1u Jul 23 '18 at 12:56
  • @ov1d1u a quick google search for "Ford Focus 2008 ECU location" (Google actually autocompleted the query as soon as I got to "EC") turns up this forum post; it's apparently between the battery and the air filter. – Doktor J Jul 23 '18 at 18:24
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Before doing anything - charge your car battery. Common problem of weird electrical issues is depleted battery (often because of it's age). If you have voltage meter (handheld multimeter or even lighter socket voltmeter, don't use the gauge test to get the voltage) you can check if the voltage is correct (should be above 12V when engine is not running and about 14V when it's on - keep in mind that Ford uses smart charging so voltage like 13.5V or 14.5V are acceptable when car alternator is working).

Next thing, quite common with Focus Mk2, is faulty soldering in the main dashboard gauges assembly. When something like this happens, try hitting the gauge hood. If it helps, there ya go - take them out, disassembly and resolder main connector (or give it to somebody for resoldering, it shouldn't cost much and anyone in local TV/electronic repair service should be able to do it.

It not the gauges, have a look in the fuse box located "in the feet" of the passanger. In Mk2 the fuse box sometimes drops and the connectors could disconnect causing various electrical issues.

Also check for leaks, especially of the coolant. In Focus coolant leak from the heater unit could go right into the fuse box (great job, Ford engineering ;) ) so take a look there as well.

And finally, check for other faulty electrical connections under the hood. Incorrect ground connection between components might cause the effect demonstrated on your video - the "leaking" voltage causes other indicators to light.

  • Thanks for your answer, Mark! I was planning to buy a multimeter and check the battery, I read on the Internet that low battery can cause this sort of behaviour, although I doubt the battery is the culprit here, as I'm able to get the roof off and then start the engine without any problem. I also found about the faulty soldering on Mk2, so I'll check for that when I get home. Now that you mentioned water I remember that some time ago I drove with my car in a flooded area - while the water level wasn't high, maybe 10cm (0.3 feet) it's likely that the water splashed into a sensitive area. – ov1d1u Jul 23 '18 at 12:43
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    @ov1d1u electrical roof as well as starter are just engines. They might work with quite low voltages. Electronics on the other hand might fail when the voltage drops under certain thresholds. Personally I don't think that's the cause (at least not the only one), because your engine is running fine, there is no alternator fault indicator visible. Yet many problems are related to the voltage issues so it's always reasonable to seek for the problems with fully charged battery. – Mark Jul 23 '18 at 12:50
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    @ov1d1u also, take your car to a parts store, many will do battery tests for free (on the premise of selling you a new battery if yours is bad). These battery tests are much more comprehensive than a multimeter (testing ampacity, etc) and can highlight problems a multimeter can't, at least not without a lot of other equipment. – Doktor J Jul 23 '18 at 18:25
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The issue was the cluster itself, as soon as I replaced it the issue with the snow light and the autopilot light has disappeared. Seems that this is a common fault with Ford Focus. The issue wasn't an electrical one so the P2566 code is genuine, I bought a new sensor and I'll have it replaced soon. Thanks for all the answers!

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