Hello fellow Focus-owners,

My car is Focus 1.6Tdci 2008 Mk2.5, Situation is this: From time to time "engine malfunction" light lights up. This happens something like once a month. Have been doing this since May when I bought the car (so probably already earlier with previous owner). I check the fault codes and only code there has been is the U0073 (Ctrl Mod Comm Bus Off) which seems to be pretty common fault code. I should mention that the car doesn't go to any limp mode or doesn't have any other symptoms besides this engine malfunction light and fault code.

Once this engine malfunction has come after hard braking and sudden stop and yesterday it came up after I drove a bumpy forest road. So based on these I was thinking that is there some loose or corroded contact somewhere in the can bus lines? Or maybe some grounding issue? What would be the best location to start checking contacts? Or does someone has any other ideas what might be the problem?

Thanks mates,

Kyde

Check this it isn't a code http://engine-codes.com/qa/14232/u0073-ford-any-idea-on-where-to-locate-the-fault

Aah, ok. Well that clarifies the code. Unfortunately it doesn't help with the "engine malfunction" light. Any ideas with that one? Still might be loose or corroded contact based on the original post? Or completely something else?

E: Seems that some people are having similar problems: http://www.fordownersclub.com/forums/topic/24021-random-engine-malfunction-warnings/

The problem with these intermittent lights is so many things can cause them a loose wire to a multitude of things best bet would be to sit someone in the car as you juggle wires and see if the light comes up

Thanks for the tip artscot79. That might be the only way to locate the problem. I was hoping that there would be some well known location which would cause this problem.

I had a longer trip (1200km) last weekend. During the trip I had this engine malfunction light 3 times. One thing I noticed was that after the light the cruise control buttons on the wheel were not working. I don't know if this is related to the issue? Need to check this again once the engine malfunction comes next time.

Update to this matter. Again I had this "engine malfunction" light twice. Now I noticed that when I press the info display button / reset button when the light is on, I can see the reason for the malfunction. Reason seems to be "Brake Light Fault". So it might be that there is some grounding issue somewhere related to the brake lights. Anyone else has any ideas to this?

what are you using to check the codes? you might want to try using a modified ELM cable and forscan to read the codes,

Chinese Bluetooth OBD -reader with Torque app. I haven't heard about this Forscan before, but it seems that it's much better than these universal free apps. I think I'll order the cable and download the software. Let's see what happens. Thanks for the tip mate!

yeah a normal obd scanner wont show you everything. get one of these: http://www.ebay.co.uk/itm/ELM327-OBD2-USB-Modified-Switch-Forscan-Elmconfig-Ford-Focus-Mondeo-Mazda-/151761960348?hash=item2355b7bd9c

and download forscan from here http://forscan.org/download.html

Den 2015-08-17 klockan 08:10 sa Kyde:

Kinesisk bluetooth OBD-läsare med Torque-app. Jag har inte hört talas om denna Forscan tidigare, men det verkar som att det är mycket bättre än dessa universella gratisappar. Jag tror att jag ska beställa kabeln och ladda ner programvaran. Vi får se vad som händer. Tack för tipset kompis!

Hej Kyde har du löst problemet? hände samma med vår Focus. Kommer upp motorfel och sedan tappar bilen kraft. Vi har bara läst med OBD som säger felkod U0073.

 

Vad var felet på din och är det lagat nu?

8 hours ago, jenny_pettersson79 said:

Hej Kyde har du löst problemet? hände samma med vår Focus. Kommer upp motorfel och sedan tappar bilen kraft. Vi har bara läst med OBD som säger felkod U0073.

 

Vad var felet på din och är det lagat nu?

Jag tvivlar på att du får svar, den här tråden har varit vilande i 7 år

That was a very polite answer Roger. Some may have been a little more direct 🤣

Greta Thunberg berömmer din ansträngning att försöka återvinna en så gammal tråd.

Hello man

How did you solve it cause i have the same thing “engine systems fault” with U0073-21 code?