Help my P5 has an CEL Codes that says Thermostat

B

Bebotech

Member

:

2002 MP5

• Jun 19, 2014

• #1

Mazda Friends,

One of my P5 has the CEL on and when plugged to the scanner it says that it is the thermostat. How could it be the thermostat? I see no sensors in the thermostat. Could someone please

advise if this ever happen to them and what may be causing this problem?

Thanks,
Bebotech

 

T

tweety2300

Member

:

2001 mazda protege mp3

• Jun 19, 2014

• #2

What's the code?

 

K

kms1990

Member

:

2011 mazda 3 hatchback GT

• Jun 19, 2014

• #3

p0128 coolant temp below thermostat regulating temp is what he possibly has that would be either low coolant level thermostat stuck open or faulty coolant temp sensor

 

B

BobbleCat

Member

:

2002 Pro5 Midnight Blue

• Jun 19, 2014

• #4

Check coolant level in the reservoir, if low tow up, then check if the code is gone.
If it isn't that then I'd look into replacing the the thermostat because it most likely is stuck or toast.

 

T

tweety2300

Member

:

2001 mazda protege mp3

• Jun 20, 2014

• #5

Sounds more like the temp sensor or low on coolant. Most cars have 2-3 temp sensors one is for the gauge then 1 or 2 for the fans and ecu

If coolant is fine check the temp sensors with a multimeter, you will have to look up voltage. It's usually one in the radiator one on the block and one on a coolant line. If thermostat was stuck you would be overheating but being 10 years old I would replace it with a fail safe as preventative maintenance, make sure to get a fail safe and not cheap out as the cheap ones tend to fail within a year and it doesn't take much to warp an aluminum head

 

Last edited: Jun 20, 2014

B

Bebotech

Member

:

2002 MP5

• Jun 20, 2014

• #6

I have noticed that the temperature is very low. When I was driving from Florida to Pennsylvania there were time when the temp gauge was showing almost zero degrees. Currently the fans are wired to be on at all times and the car has an intake.

 

T

tweety2300

Member

:

2001 mazda protege mp3

• Jun 20, 2014

• #7

Well that's probably why the cel is on. Your tstat is probably stuck open, replace it clear the code and you should be good

 

B

Bebotech

Member

:

2002 MP5

• Jun 20, 2014

• #8

So there is a sensor that tells if the thermostat is open?

 

P

P-Funk!

:

Lancer Ralliart Sportback

• Jun 20, 2014

• #9

ECU logic looks for engine temps to rise xxdeg above ambient after a YY period of time.

 

B

Bebotech

Member

:

2002 MP5

• Jun 20, 2014

• #10

Ok, thanks.

 

B

Bebotech

Member

:

2002 MP5

• Jun 20, 2014

• #11

Well it look like the coolant level was low, however the light is still on. I guess run the car for a while to see if it shuts off.

 

T

tweety2300

Member

:

2001 mazda protege mp3

• Jun 20, 2014

• #12

No, replace the tstat. Cel is on because it's runing colder than it's meant to. Car is made to run in a specific temp range. Runing it too cold is almost as bad as runing it hot

 

K

kms1990

Member

:

2011 mazda 3 hatchback GT

• Jun 21, 2014

• #13

i would replace both temp sensor and tsat their cheap and easy to do.

 

B

Bebotech

Member

:

2002 MP5

• Jun 23, 2014

• #14

Ok, guys I got a code. The code that is coming up on the scanner is P0128 and there are different options as to what might be wrong does anyone know exactly what I need to replace?

 

T

tweety2300

Member

:

2001 mazda protege mp3

• Jun 23, 2014

• #15

I've already stated it. You already know what to replace. So why not just replace it?

 

M

mp5la

Member

:

2002 Mazda Protege 5

• Jun 23, 2014

• #16

The thermostat only takes about twenty minutes to replace. The hardest part of the whole process is draining the coolant and not making a mess. Given the age of these cars, why not try replacing the thermostat and resetting the ECU? Worse case scenario, a code comes back and you've eliminated the most likely culprit. Just use a quality thermostat (no autozone junk).

 

B

Bebotech

Member

:

2002 MP5

• Jun 23, 2014

• #17

I am just trying not to start buying a whole bunch of parts that will not contribute to fixing the problem. I can start buying things that will not fix the problem, that is money down the drain.

 

B

Bebotech

Member

:

2002 MP5

• Jun 23, 2014

• #18

tweety2300, I thank you for your help, and I know that you have already said what you would replace. However, someone asked me for the code earlier on and I thought of sharing that information with you guys. I don't want to start buying parts like crazy. I really appreciate your help.

 

M

mp5la

Member

:

2002 Mazda Protege 5

• Jun 23, 2014

• #19

Bebotech said:

I am just trying not to start buying a whole bunch of parts that will not contribute to fixing the problem. I can start buying things that will not fix the problem, that is money down the drain.

Click to expand...

I totally get that. If you've never changed the thermostat on the car though, there's no telling when its been changed. A twelve year old thermostat is definitely something I would replace regardless just as preventative maintenance. If it fails, it'll cause a lot more damage than the roughly $20 price of a t-stat and some coolant. Ultimately, it could fix the code on the car, but if it doesn't that's ok too. It probably needs to be done anyway.

 

B

Bebotech

Member

:

2002 MP5

• Jun 23, 2014

• #20

You are right I will replace this item Today.