Hi all,

I’ve got a leaking camshaft solenoid valve on my 2021 Focus 1.0 125HP (manual). The oil seems to be seeping into the wiring, and I’ve seen a few other posts here about similar issues. I was quoted around 1200 for the repair, which seems a bit steep for what looks like a fairly straightforward job.

I’m considering tackling it myself — has anyone here done this before? Any tips or things I should keep in mind?

From what I can tell, the intake and exhaust solenoids share the same part number (CM5G6M280), so I assume they’re interchangeable?

Appreciate any advice or experiences, thanks

Changing the solenoids is the easy part.  

The loom damage is what you're paying for.  Would you be replacing the full loom with a used one?  Or replacing individual wires?

At this point I just were thinking to change the soleinoids since the leak is minor (quoted from the service) and will stop the leak. Do you think that is just a temporary fix and will cause more problems in the future?

Is the solenoid change just taking 3 bolts out and putting new one in?

13 hours ago, Dunkirk said:

At this point I just were thinking to change the soleinoids since the leak is minor (quoted from the service) and will stop the leak. Do you think that is just a temporary fix and will cause more problems in the future?

Is the solenoid change just taking 3 bolts out and putting new one in?

If there's oil in the loom already, it's too late to save that.  There's no way to clean it out.  The affected wires will need to be replaced at some point.

The solenoid change is as simple as you describe.

5 hours ago, TomsFocus said:

If there's oil in the loom already, it's too late to save that.  There's no way to clean it out.  The affected wires will need to be replaced at some point.

The solenoid change is as simple as you describe.

I've often wondered what harm Oil between the Conductor and Insulation does even if it reaches the PCM. 

I would Imagine that very old Oil could be corrosive and that it is non¬conductive, do you or anyone else have sny ideas Tom? 

4 hours ago, Tizer said:

I've often wondered what harm Oil between the Conductor and Insulation does even if it reaches the PCM. 

I would Imagine that very old Oil could be corrosive and that it is non¬conductive, do you or anyone else have sny ideas Tom? 

No, I must confess this is one of few faults I haven't experienced myself and am just repeating internet hype on the subject.

It seems to happen on a lot of modern engines, not just Fords.  And I do see fault fault codes being flagged up, though it's hard to tell whether that's due to loom damage or the original sensor being faulty as both are generally fixed at the same time.

Only thing I will say is that even fairly new oil is likely to be contaminated with fuel from direct injection and exhaust from high compression turbocharging nowadays, as well as absorbing moisture from the air.  I suspect oil does become acidic pretty quickly nowadays, which is the reason wetbelts are such an issue in the real world compared to lab tests.

I had this exact issue at 35k miles on my mk4 focus, Contaminated wiring loom taken out both oxygen sensors and knock sensor. New Wiring loom, both oxygen sensors and knock sensor ended me with a 1600 bill from ford. 

On 4/10/2025 at 10:25 AM, TomsFocus said:

If there's oil in the loom already, it's too late to save that.  There's no way to clean it out.  The affected wires will need to be replaced at some point.

The solenoid change is as simple as you describe.

Hi TomsFocus, I've replaced my solenoids for new today and after a run I'm pleased to say dry as a bone unlike the leaky old ones. I have a recurring sensor 2 downstream heater circuit code. Now I've sorted the oil leak and seems to have cleaned all visible oil from the loom connectors (3 goes with brake cleaner and left to drain dry), no oil showing in any other connectors, I was wondering if the loom replacement is critical before the O2 replacement? I'm wanting to keep costs down as I'm looking to trade in soon and just need the fix to last me for a month or two. So wondering if thoughts are the code it a failed O2 sensor or oil causing the code to be created?? Cheers for any advise.

4 minutes ago, miffmoo said:

Hi TomsFocus, I've replaced my solenoids for new today and after a run I'm pleased to say dry as a bone unlike the leaky old ones. I have a recurring sensor 2 downstream heater circuit code. Now I've sorted the oil leak and seems to have cleaned all visible oil from the loom connectors (3 goes with brake cleaner and left to drain dry), no oil showing in any other connectors, I was wondering if the loom replacement is critical before the O2 replacement? I'm wanting to keep costs down as I'm looking to trade in soon and just need the fix to last me for a month or two. So wondering if thoughts are the code it a failed O2 sensor or oil causing the code to be created?? Cheers for any advise.

The sensor heaters do burn out over time, but on a 2020 model it is more likely to be a wiring fault.

The heaters are really simple, literally just a coil of wire, so you can test them easily with multimeter.

I'm not sure what access is like for the post-cat sensor in a Mk4 though.

Thanks for that, I tried to test the two white wires to measure the ohms the other day, they seemed to measure 0 hence a broken coil. The post cat O2 was actually replaced a year ago with an after market when I assume this all started but was then fine for 6-8mths. Who knows if the quality was right in a cheap one however. I may disconnect again tomorrow and get better access to be 100% the coil is bust. Do you know where I would start to find out what loom I need? There's some on eBay but just wondered if there was a specific name for it? Cheers again!

19 hours ago, miffmoo said:

they seemed to measure 0 hence a broken coil.

The resistance of the heating element is very low. I don't have an exact value but it will typically be less than 5.5 Ohms

If the element was broken (open circuit) then the meter would display 'OC' or Infinity.

If your meter is showing 0.0 Ohms then that is a short-circuit and would indicate a wiring fault rather than the actual heater element.

 

Great advise thanks, as I mention I tried to get a reading in a tight space, I will have a much better go tomorrow by getting the tray off and on the ramps and check the reading with a good connection and room to play. Going from the top is tight.

11 hours ago, miffmoo said:

Do you know where I would start to find out what loom I need? There's some on eBay but just wondered if there was a specific name for it? Cheers again!

Looms are awkward to find on the parts catalogue as there are so many variations.  There will be a part number on a white sticker on your loom somewhere.  If you can find that, then you can match it to any replacement on ebay.

So got much better access to the sensor 2 connector today, I was incorrect saying the reading was 0, it's 1 (or more likely I for infinity as Unofix advised). I tested the 2 white wires which research suggests were the heater wires and if there was no ohms, it suggests a faulty element like the code says so I will go ahead and order that first to see if that cures it as the rest of the loom looks mint although I know it maybe contaminated inside the wiring. If anyone is able to concure that the heater circuit looks to be dead that would give me some piece of mind. Thanks so much for your help so far!

2 hours ago, miffmoo said:

more likely I for infinity

👍

The heating element would seem to be open-circuit. 🙁

O2 sensor on order, let's see if this step sorts it 🤗 thanks 👍👍

On 15/5/2025 at 10:17 ΠΜ, miffmoo said:

Αισθητήρας O2 σε παραγγελία, ας δούμε αν αυτό το βήμα θα το λύσει 🤗 ευχαριστώ 👍 👍

i have the same symptoms (ford focus mk4 1.0 125 ps b7da) and i have already ordered a new o2 senssor 1 bank1 (upstream) . what happend with your case? did you fix the problem???