Hi everybody!

I have a 2012 focus with the 1.6 ti-vct engine. I’m the second owner of the car and it only had 94k kms. Recently it had the timing belt replaced. It was all well until the day after it was serviced. I was driving normally home when the check engine light came on and after a while the hill start assist and the stability control turned off. I took the car back to the mechanic the next day and we checked for fault codes. The computer said the engine was deprived of air. After this the car was taken to a ford service center but they couldn’t do anything since they didn’t have the wiring schematics. They cleared the fault codes and I drove off. The next day the engine light came back and the car started basically choking and couldn’t idle smoothly. I gave it a little bit of gas to see if that could fix the idle but the engine made a clunking noise after I let off the gas so I shut it off. About 8 hours later I had to drive home and the engine light started flashing and the car wouldn’t accelerate normally and smoothly. I was thinking that the O2 sensor’s wiring got damaged during the timing belt service and that’s why the engine is choking since the mechanic didn’t unplug anything but instead just moved everything to the side. 
What are your opinions?

51 minutes ago, Mark03 said:

What are your opinions?

My idea would be to stop guessing and do some logical fault finding.

Start by using FORScan to read the Ford specific DTC's which there has to be since you have the EML on. You could also measure the battery voltage with a multimeter and find out what that is.

My opinion is to check to ensure that the engine is still in time after the cambelt change. To me it sounds like the timing might be out, but by not by much.

Otherwise I'd double check that the wires the garage had to disconnect to do the job, to make sure nothing was left disconnected. Otherwise you need to do what unofix suggested, check the battery has charge and connected correctly, namely the terminals are tight and connected correctly. Check the codes to get a direction of what you should be looking at to cause the codes to arise. 

1 hour ago, King683 said:

My opinion is to check to ensure that the engine is still in time after the cambelt change. To me it sounds like the timing might be out, but by not by much.

Otherwise I'd double check that the wires the garage had to disconnect to do the job, to make sure nothing was left disconnected. Otherwise you need to do what unofix suggested, check the battery has charge and connected correctly, namely the terminals are tight and connected correctly. Check the codes to get a direction of what you should be looking at to cause the codes to arise. 

I forgot to mention that after the first incident they double checked the timing with a tool from ford and they said it was perfect. Sadly I’m not a mechanic so the most I can do is guess at the moment because the service won’t do anything about it untill they have the wiring schematics. Also the person who did the job said that they didn’t unplug anything and that’s why I think that they broke one of the cables or connectors of the O2 sensor.