V70 strange fault today
 

Whilst driving today, my V70 developed a fault that felt like it was misfiring (felt like my first Mk2 Escort when it had two knackered spark plugs). Two warnings were displayed on the dash. DTSC service required and Engine system service required.

I stopped it and restarted - same codes and issues.

Used my cheap OBD2 reader and the following codes are showing.

P1264 ECU Cylinder 4 High To Low Side Short
U0415(68) Invalid data received - anti-lock braking system (ABS)
P2425(00) EGR valve cooling valve - open circuit

Any ideas of the issues and the fixes?

I think just diagnosing from those three codes alone will be a task and a half.

The only input I have is based on another vehicle brand. On my Smart Roadster when an ABS sensor fails or the reluctor ring on the driveshaft splits or becomes overly rusted, the car develops a misfire. The last occurrence was split reluctor causing a rogue signal, previous to that a sensor just failed.

Perhaps you could take a look in this area.

What you really need is Vida so you can see the live data and use the diagnosis portion to work through.

Code readers only - They are for the wizards amongst who recognise a series of codes from previous experience.

Perhaps a wizard will be along shortly...

Does it do it whilst cornering at relatively low speeds? Like driving around town?

I think tommyweaves might be referring to a potential faulty wheel bearing with play in it that alters the abs sensor to reluctor ring air gap hence the error code.

Remember that the ABS not only controls brakes but can cut fuelling and/or throttle - it will be linked through the ESP which works by controlling brakes and engine speed
the latter of which might be the misfire you have experienced.

Let us know how you get on

Correct!

No, it just cut in without warning on an A-Road at around 40mph. Constant misfire and worse with more throttle, but not noticeable with foot off throttle. I only drove it home.

Starting it since, the misfire now continues at idle in neutral. Like a cylinder isn’t firing at all

Your ABS code would tie up with the DSTC service required message, but I'd expect your ABS light to stay on at the same time.

The "misfire" at idle issue doesn't logically have a direct relation to ABS/DSTC issues.

Therefore I wonder if you have 2 separate unrelated issues occuring at the same time.

I'm assuming you can clear those codes through your OBD2 and see if they immediately return?

A full code read/VIDA is really the best way forward as has already been mentioned.

Thanks and yes, ABS light is on too. I haven’t cleared the codes yet, but can and will do soon. My suspicion is that the issue is reluctor ring related, causing an intentional misfire and the misfire continues as the code is stored. If the code clear allows it to run smoothly until I move it again, I suspect that the issue and codes will return.

Unfortunately on the P3 V70s you have to replace the wheel bearing as the tone ring (as they call it) is integral to the bearing, rather than on the P2 where the reluctor ring was a separate replaceable component.

I disabled DSTC using the left stalk and that helped in terms of diagnosing the wheel speed sensor issue. You have to disable at the beginning of every trip I seem to remember.

Thanks, your tip for diagnosis is very helpful. Are you absolutely sure on the integral tone ring? Most motor factor sites advertise these separately for my car.