Incorrect outside temperature displaying on trip computer

[Jp90]

Hi, I was wondering if someone on here could possibly help me out.

I'll start from the beginning, I have a 2014 Ford Focus 1.6 TDCi which I've never really had issues with service regularly etc. 
Since lockdown I've not really driven the car and about a month ago took it out and got the "Engine Malfunction service Now" message displayed and the car went into limp mode, I've had this once previously in 2018 and it turned out to be a fuel filter issue which I got sorted. I took it to a garage where they identified the fault via and OBD readers as an MAF sensor issue. The fault was reset as a part wasn't immediately available and due tot he current situation they wouldn't get one delivered for a few weeks. I was sent on my way and the car was fine for a few days. Then the exact same thing happened again, fortunately I was about 1 min from the garage and again the identified the fault as an MAF sensor fault, they cleared the fault and updated me RE: My original order.

So maybe this is where I messed up, I got impatient (I'm moving house this week) and done a bit of my own research and sourced a HAAS MAF sensor (not the unit just the card). I replaced the sensor with no issue, done all the regular things such as disconnecting the battery first etc. I started my car and everything was fine, apart from the engine light was on. I spoke to a mate who has and OBD reader who came round and cleared it off for me, double checked what I had done and said it looked good to him. This is where this minor problem starts. 

My outdoor temperate is displaying as -40c and the aircon doesn't work it just blows in outside air. While driving the temp will slowly start increasing until it reaches what the actual outdoor temp is and the aircon also starts working at around -26c (earlier this afternoon it did go back into limp mode, I pulled over turned the ignition off for 5 mins and tried again and it was fine). Is there anything with replacing the MAF that would cause this or is it a separate issue,?

[MasterTechTip]

Hi, yes disconnecting or replacing the MAF sensor will put the outside temperature to -40 but this usually only happens if it is done with ignition on. The reason it does this is because the MAF also has a temperature sensor built into it (MAFT). It does take a while for the temperature to go back to normal. Also your AC doesn't work below 0 (may vary from vehicle to vehicle) so as the temperature is reading well into the minus it won't operate for that reason, hope this helps!

[Jp90]

Hi, thanks for getting back to me. I did think this may be the case regarding the temperature sensor.

As far as I'm aware the ignition was off when I replaced the sensor, but I might be wrong. Do you know roughly how long this takes to go back to normal or is it just a waiting game?

 

 

[MasterTechTip]

Waiting game I'm afraid there's no way I know of to make it change quicker. 

[Jp90]

Well that’s a bit annoying, sometimes when I start it the correct temp is displayed and other times it says -40 ha. So guess I’ll just wait. 

[MasterTechTip]

If it is resetting every time you turn the car on then I suspect there's a fault with either the MAFT or wiring 

[Jp90]

1 hour ago, MasterTechTip said:

If it is resetting every time you turn the car on then I suspect there's a fault with either the MAFT or wiring 

I’ve got a sneaky suspicion this may be the case. Went to the shops earlier and it was fine displaying 24c. 
 

Just started it again and it’s displayed -40c

[MasterTechTip]

I don't know how handy you are with wiring but I'd check the pin grips on the connector to make sure there's good contact, if the contact is poor then this could be giving you your issue as it keep connecting and disconnecting if that makes sense? Either that or the sensor you have is a bit dodgy

[Jp90]

Ahhh nice one, I know my way around so will check. If not I know a few people that can help out with this. 
 

thanks a lot for your help. 

[MasterTechTip]

No problem hope you fix it!

[Jp90]

Resurrecting this as my issue is still ongoing.

I haven't managed to find anything relating to a MAFT sensor, I have replaced the MAF twice now with the same result (different brands). I have checked wiring but not much I could see there. I did manage to connect an OBD reader and see which codes come up (see photos)

Any tips? Or if its a particular part I need would it be possible to link me to this?

Thanks again.

 

 

[MasterTechTip]

Hmmm I'd suspect you have a wiring issue between the PCM and the sensor. You'll need to strip the passenger front wheel arch lining to gain access to the PCM and then get the PCM cover off. This has 3 security bolts that you will need to either drill out or I cut a straight line through them with a disc cutter and then undo them with a flat head scewdriver. This will leave cuts in the cover as well.

You'll then have to remove the connectors on the PCM and test from the wires at the connectors to the sensor (both disconnected) test for resistance, isolation from earth and I'd load test the wiring the too with a 21W bulb. Do not put voltage directly into the PCM or it may break. 

This will be quite challenging and you'll need a wiring diagram.

[Jp90]

Great thanks, I've had a look around the engine bay etc as well and have found 2 things that concern me. (see images)

1. The wire coming from the MAF sensor (I don't know what this connects to on the other end) is held together with insulation tape, i haven't peeled it off but I suspect the issue might lay here. 

2. Another quick was made with the air intake hose, it doesn't quite look right to me... is this worth changing too?

 

 

[MasterTechTip]

6 hours ago, Jp90 said:

Great thanks, I've had a look around the engine bay etc as well and have found 2 things that concern me. (see images)

1. The wire coming from the MAF sensor (I don't know what this connects to on the other end) is held together with insulation tape, i haven't peeled it off but I suspect the issue might lay here. 

2. Another quick was made with the air intake hose, it doesn't quite look right to me... is this worth changing too?

 

 

 

so your hoses look fine but if you zoom right in on the first picture I'm pretty certain I can see broken wires and copper strands frayed out. Definitely get that tape off!