Focus Fanatics Forum banner
1 - 11 of 11 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter · #1 ·
Hi all. I have a 2006, Ford Focus SE with a 2.0l Duratec motor, 5 speed transmission. I pulled a P0128 error code today. The temp gauge reading is normal but the car is running very rough and the cel is on. I have been searching all afternoon for the location of the coolant sensor.[?|]
I know where the cylinder head sensor is but I can't find anything showing where the coolant sensor is.
Am I correct that this car uses separate sensors for the head and coolant? If so, where the heck is the coolant sensor? Some pictures would be great.
I've found plenty of info on the older motors with distributors and the SOHC motors and the Zetec motors, but nothing on this DOHC Duratec motor.
BTW, I did a search on this forum and couldn't find anything helpful.
 

·
Registered
Joined
·
9 Posts
After fooling around with my 2009 Focus SES cooling issues, this thread although not directly related to your concern may help you in the end...

My symptom was that after an accident, and my car being taken out of a shop that did not handle the repairs of my car, I ended up with a non working radiator fan under any circumstance - AC on, etc.

Number one thing to do: Start from the very basic troubleshooting steps.

1. Check fuses - My 20 amp low speed had been removed
2. Check relays - Power is always on at the high speed relay, and if jumpered on the large terminal side, power will show now at the low speed relay. If the harness is good to the fan motor, it should spin.

Yet, my fan did not spin. I looked at the harness, and saw no damage nor any reason to doubt the power leads (Hi, Lo) were good to the fan. Either the fan is dead, or I am missing a connection to ground...

On the passenger side under the radiator bottle on the 2008-2011 models is a ground lug... It was removed. As soon as I touched the frame it sparked... I cursed the person that lifted this ground. If this lug had any issues, you would have problems with the fan... remember you are grounding up to 30 amps so it is an important connection.

Lastly, there is a reason the car runs bad when there are cooling issues. It is listed in your owners manual as "failsafe mode". When the cylinder head temp sensor indicates high temps, the PCM starts cutting out injectors to "air pump" the motor to cool the head. We notice a poorly running engine and a check engine light (the wrench in my case).

While the failsafe mode may not stop a car on the freeway from cracking a head, it does say to the driver, "Hey, I am seriously ill. Fix me."

My cooling system is back to normal, and I can see how it would be very easy to overlook a bad ground or no ground condition with that ground lug placed under the radiator overflow bottle. The cooling system isn't as complicated as it sounds, and is more durable than we think notwithstanding the failing sensors and melted plugs which thankfully wasn't my problem.

If the head says it is hot, and is tripping the failsafe mode, I would work real hard to disprove the temperature issue before I replace the cht sensor. Make sure your fan or fans in the case of older models is concerned are indeed running and the car is cooling itself down... and of course, make sure the coolant level is correct. Nobody wants to fix a cracked or warped head... and the PCM will do all it can to avoid it by making your car run like crap or not at all. It will kill all 4 injectors trying to cool the head if alternating 2 at a time doesn't work...

LJ
 

·
Registered
Joined
·
4,529 Posts
...I know where the cylinder head sensor is but I can't find anything showing where the coolant sensor is...
The coolant sensor should be on the T-stat housing and would include a female electrical connection HOWEVER I have never seen a 2003-2007 Duratec engine Focus with a coolant sensor. The Focus with a T-stat coolant sensor is a unicorn until someone stands up with an update. I am also waiting to run into this, hear about this, with newer 2008+ Foci.

@LJ - Great info, thanks for sharing.
 

·
Grey Friar
Joined
·
1,275 Posts
...My symptom was that after an accident, and my car being taken out of a shop that did not handle the repairs of my car ...

...On the passenger side under the radiator bottle on the 2008-2011 models is a ground lug... It was removed. As soon as I touched the frame it sparked... I cursed the person that lifted this ground. ...
I couldn't make sense of the first sentence, but it sounds like the car was moved from one shop to another. If so, the unhooked ground wire could be a spiteful action on part of the first shop, or else it's bad work at the second shop. If you have any reason to think it was disconnected and not reconnected by the second shop, I'd call and complain, then never take my car there again... unless they offer some sort of free compensation.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #6 ·
After much fooling around I think I finally understand the temp sensor situation. In the Ford Focus 2007, with the 2.0L Duratec motor Ford uses just one sensor for both the cylinder head and coolant temps. The sensor is located in the head between the 2nd and 3rd sparkplug.
If you need to replace the sensor you may find that the new sensor doesn't look like the old one. The brass section on the factory installed sensor is about 1.5" long and the new one is half that length. Ford updated the design at some point. Most clerks don't know this, not even at the dealership. I wasted a LOT of time because I thought they kept giving me the wrong part.[?|] Also, the new part requires a replacement wiring harness. This usually comes boxed with the new part but sometimes the dealers sell it separately. My local dealer tried to charge me an extra $50 just for the harness (it actually cost $20 more than the sensor![:(!]).
Finally, if you pull a trouble code P0128, this simply means that the computer is getting a lower than expected motor temp reading. This could be caused by the sensor or the thermostat. The sensor is about $35 and takes 10 minutes to swap out, most of that time is just soldering in the new harness. The thermostat is anywhere from $65 to $145 and takes 2 - 3 hours to replace plus all the coolant. So, I started with the sensor even though many people argue that the problem is usually the thermostat.
 

·
Focus Hoarder
Joined
·
3,633 Posts
After much fooling around I think I finally understand the temp sensor situation. In the Ford Focus 2007, with the 2.0L Duratec motor Ford uses just one sensor for both the cylinder head and coolant temps. The sensor is located in the head between the 2nd and 3rd sparkplug.
If you need to replace the sensor you may find that the new sensor doesn't look like the old one. The brass section on the factory installed sensor is about 1.5" long and the new one is half that length. Ford updated the design at some point. Most clerks don't know this, not even at the dealership. I wasted a LOT of time because I thought they kept giving me the wrong part.[?|] Also, the new part requires a replacement wiring harness. This usually comes boxed with the new part but sometimes the dealers sell it separately. My local dealer tried to charge me an extra $50 just for the harness (it actually cost $20 more than the sensor![:(!]).
Finally, if you pull a trouble code P0128, this simply means that the computer is getting a lower than expected motor temp reading. This could be caused by the sensor or the thermostat. The sensor is about $35 and takes 10 minutes to swap out, most of that time is just soldering in the new harness. The thermostat is anywhere from $65 to $145 and takes 2 - 3 hours to replace plus all the coolant. So, I started with the sensor even though many people argue that the problem is usually the thermostat.
that sounds about right to what was being told.. and that actually sounds about right about the prices.. what i dont get is why they are selling you a sensor that has a different end thats a red flag right there???
unless something is known and not being told to the public about maybe the plug itself having a inherent issue..
the only time the factory harness would ever be replaced is if the wire broke going into the plug, it was corroded or melted.

the only time ive seen a part use a different plug (but the pigtail was only $6.99) was when they revised the 2000-2002 Zetec Focus throttle position sensor which in turn needed a new throttle body and pigtail aswel.

something sounds really odd with this and im probably going to go take a peek at the Ford dealers stock for that part.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #8 ·
that sounds about right to what was being told.. and that actually sounds about right about the prices.. what i dont get is why they are selling you a sensor that has a different end thats a red flag right there???
unless something is known and not being told to the public about maybe the plug itself having a inherent issue..
the only time the factory harness would ever be replaced is if the wire broke going into the plug, it was corroded or melted.

the only time ive seen a part use a different plug (but the pigtail was only $6.99) was when they revised the 2000-2002 Zetec Focus throttle position sensor which in turn needed a new throttle body and pigtail aswel.

something sounds really odd with this and im probably going to go take a peek at the Ford dealers stock for that part.
I don't think it's anything nefarious. I think they just switched to a different sensor in all the other applications and didn't want to keep supporting the old style anymore.
As far as the harness is concerned, the plug configuration of the new sensor is slightly different than the old one. That's why the new harness.
I'm sure it's possible to find the old style but why bother if they are compatible?
 

·
Focus Hoarder
Joined
·
3,633 Posts
again i worked for ford ive never come across a change other then the TPS on the focuses that needed a pigtail replacement. if you know how to solder ask how much the pigtail kit for it is.. again pigtails are usually under $10 so a $50 adapter seems uhmm out there.

but again this is me and im known to just visit the local scrap yard and shop for a clean sensor/part and only pay $5-$10.
ive personally never had a scrap yard part be bad and they usually end up lasting for several more years or until the cars written off or the canadian rusties get to the subframes
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #10 ·
again i worked for ford ive never come across a change other then the TPS on the focuses that needed a pigtail replacement. if you know how to solder ask how much the pigtail kit for it is.. again pigtails are usually under $10 so a $50 adapter seems uhmm out there.

but again this is me and im known to just visit the local scrap yard and shop for a clean sensor/part and only pay $5-$10.
ive personally never had a scrap yard part be bad and they usually end up lasting for several more years or until the cars written off or the canadian rusties get to the subframes
Thanks for the advice. I've already soldered the pigtail and installed it. As I said, it took less than 10 minutes.
 

·
Focus Hoarder
Joined
·
3,633 Posts
Thanks for the advice. I've already soldered the pigtail and installed it. As I said, it took less than 10 minutes.
woa wait... they charged you $50+ for the pigtail>>> when people say adapter its usually a short wire with 2 ends that are not the same to adapt one plug to another not hack the end off and solder a new end on which is referred to is a pigtail
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top