Since it happens when its cold i would expect it to be low but not low enough to trigger the code i recommend checking the thermostat see what its rated at then check the engine temp in the morning right when it comes on and see the motor temp then and see how many degree's in difference it is

Correct engine temp is around 180-210 degree's so it shouldnt be much lower than that once it reaches running temp

Let me know what happens

 

I had the same issue with this code back in the early spring ( 2005 2.3s hatch mtx). There is a bulletin out for this code. I tried having the dealership do the pcm software upgrade first, but the code came back after a couple weeks. I then replaced the thermostat and that fixed the issue. After the thermostat fix I noticed the engine immediately warms up to operating temp, so the likely cause was a stuck open thermostat. The thermostat really isn't difficult to change - just requires an 8mm swivel socket and some small hands!

 

Yeah, a good way to tell if it's likely the thermostat itself, is by timing how long the engine takes to warm up to operating temp during normal driving. It should generally get up to normal temp (needle in the middle) within 5 minutes. If it doesn't, replacing the (most likely) stuck open thermostat would be the way to go.

 

I to have this issue and it takes me a lot more than 5 minutes to warm up. Is there a how-to on changing the thermostat?

 

it should be in the "power train technical FAQs/How to's section, I have the same recurring issue and have read the walkthrough, just make sure you get the genuine mazda thermostat.

 

So I fixed the problem by changing the thermostat.

Just some more background in case anyone else encounters this problem:

The light would turn on almost everyday, and I could make the light turn on just by driving it above 3k RPM within the first 5 minutes of driving. The temp gauge would not get to the middle until about 15 minutes of just sitting, no driving. Even when driving it would take about 10 minutes of driving to reach the steady level at the half. The thermostat was absolutely the issue from being stuck open.

The thermostat is really easy to change as long as you can get the car off the ground enough to reach your arm from the bottom and top to get the 3 bolts that hold it on. My buddy has a lift in his garage, so everything was easy to reach. There is about a gallon of coolant I had to replace after draining. Also, when I bought the thermostat, it didn't say it came with a o-ring, so I ordered one, but it ended up coming attached to the new thermostat. I wasted 4 bucks.


All-in-all EASY fix.

 

You are welcome I took your gasket lol

 

My CEL had been coming on recently. I took it to the dealer and they pulled the same code and replaced the thermostat. They charged me $420. That seems a little high, but I was tired of dealing with it and didn't have a great way to get under my car. After 3 days everything seems good to go!

I hadn't noticed my car being slow to warm-up so I'll have to take note tomorrow morning.

 

My daughter drives 2009 3 and complains it takes a long time to for the heater to warm up on these cold days we are having . She only has 20,000 miles on it, I'm wondering if I should replace the thermostat to see if that helps? There is no problems with check engine light or anything else.

 

I have the same problem on my 2006, how much is the thermostat? I'm at the office and Ebay is blocked along with other sites... luckily MZ3Forums isn't =D

 

chalk up another one..mine is stuck as well.

 

it isn't much of a problem right? I mean it only takes more time to warm up.... or does it affect something else? over here is not really cold, much more a hot weather so it is not a big deal to wait a bit more to warm up the engine

 

My 04 had the same code. The thermostat was stuck open and it was a $50 dealer part.

 

[quote author=Hyper-X link=topic=179467.msg3886176#msg3886176 date=1292609470]
it isn't much of a problem right? I mean it only takes more time to warm up.... or does it affect something else? over here is not really cold, much more a hot weather so it is not a big deal to wait a bit more to warm up the engine
[/quote]

A cold cylinder wall will wear out faster. The engine operating temp needs to be at least 180 degrees and optimal 200 degrees. I have experience with this and it is real. Also, the cold start will stay on longer as well as the computer will stay in open loop longer.

 

[quote author=Hyper-X link=topic=179467.msg3886176#msg3886176 date=1292609470]
it isn't much of a problem right? I mean it only takes more time to warm up.... or does it affect something else? over here is not really cold, much more a hot weather so it is not a big deal to wait a bit more to warm up the engine
[/quote]

Taking longer to warm up means the catalytic converter is not warming up as fast either so you are polluting more. Something like 90% of auto emissions occur during warm-up so you are definitely greatly increasing the pollution from your car. The check engine light is basically a pollution light.

 

My 05 gets this light occasionally. It comes on then goes off after a few hundred miles and then it comes back again. Right now it's been off all week.

Car doesn't take long to warm up. I read the TSB about the PCM software update. Mazda wanted $90 to do it so I said no. Should I worry about this or not?

 

[quote author=cyclonesworld link=topic=179467.msg3899929#msg3899929 date=1294333255]
My 05 gets this light occasionally. It comes on then goes off after a few hundred miles and then it comes back again. Right now it's been off all week.

Car doesn't take long to warm up. I read the TSB about the PCM software update. Mazda wanted $90 to do it so I said no. Should I worry about this or not?

That’s what was happening with my Daughter’s 06 Mazda3 and my 06 Mercury Milan (same 2.3 L engine and thermostat, except the housing on the Mazda is a little longer). The engine light does not come on after the replacement. The early thermostat and housing is just not a good design.

 

What about the code P0126 (Insufficient Coolant Temperature for Stable Operation). Has anyone experienced this code?

 

Have the same code P1026. Stealer wants $75 part and $ 205 labor....on top of $130 for diagnosis. Also, wants
P0506 idle valve? $705 part and $205 labor. Total, wants $2,600 for everything...

 

[quote author=rdsanti89 link=topic=179467.msg3915205#msg3915205 date=1295922241]
What about the code P0126 (Insufficient Coolant Temperature for Stable Operation). Has anyone experienced this code?
[/quote]

I got this code myself after going down a 2-3 mile grade, but it reset itself after a couple of days of driving. I suspect the relatively long period of driving downhill, coupled with the high 30s outside air temperatures probably dropped the engine temp lower than what the computer expects, thus tripping the code. I had no driveability issues, engine warmed up normally on subsequent cold starts, and mileage was unaffected while the CEL was lit.

 

[quote author=Bart link=topic=179467.msg3939545#msg3939545 date=1298124141]
[quote author=rdsanti89 link=topic=179467.msg3915205#msg3915205 date=1295922241]
What about the code P0126 (Insufficient Coolant Temperature for Stable Operation). Has anyone experienced this code?
[/quote]

I got this code myself after going down a 2-3 mile grade, but it reset itself after a couple of days of driving. I suspect the relatively long period of driving downhill, coupled with the high 30s outside air temperatures probably dropped the engine temp lower than what the computer expects, thus tripping the code. I had no driveability issues, engine warmed up normally on subsequent cold starts, and mileage was unaffected while the CEL was lit.
[/quote]

How many miles do you have?

 

[quote author=birdman579 link=topic=179467.msg3875384#msg3875384 date=1291529204]
My CEL had been coming on recently. I took it to the dealer and they pulled the same code and replaced the thermostat. They charged me $420. That seems a little high, but I was tired of dealing with it and didn't have a great way to get under my car. After 3 days everything seems good to go!

I hadn't noticed my car being slow to warm-up so I'll have to take note tomorrow morning.
[/quote]

I took my car for MD emissions testing yesterday and passed! My CEL hasn't come back on since the repair so it looks like the dealer did a good job.

 

Just shy of 75,000 on my 2007.

[quote author=LuisDC link=topic=179467.msg3939611#msg3939611 date=1298137123]
[quote author=Bart link=topic=179467.msg3939545#msg3939545 date=1298124141]
[quote author=rdsanti89 link=topic=179467.msg3915205#msg3915205 date=1295922241]
What about the code P0126 (Insufficient Coolant Temperature for Stable Operation). Has anyone experienced this code?
[/quote]

I got this code myself after going down a 2-3 mile grade, but it reset itself after a couple of days of driving. I suspect the relatively long period of driving downhill, coupled with the high 30s outside air temperatures probably dropped the engine temp lower than what the computer expects, thus tripping the code. I had no driveability issues, engine warmed up normally on subsequent cold starts, and mileage was unaffected while the CEL was lit.
[/quote]

How many miles do you have?
[/quote]

 

Looks like I'll be replacing my thermostat, since while I was driving home from PA to MD yesterday, my CEL came on. After the diagnostic test, I found that it was this code. With 110,000 miles, I can't really complain.

 

[quote author=Bart link=topic=179467.msg3939875#msg3939875 date=1298174992]
Just shy of 75,000 on my 2007.

[quote author=LuisDC link=topic=179467.msg3939611#msg3939611 date=1298137123]
[quote author=Bart link=topic=179467.msg3939545#msg3939545 date=1298124141]
[quote author=rdsanti89 link=topic=179467.msg3915205#msg3915205 date=1295922241]
What about the code P0126 (Insufficient Coolant Temperature for Stable Operation). Has anyone experienced this code?
[/quote]

I got this code myself after going down a 2-3 mile grade, but it reset itself after a couple of days of driving. I suspect the relatively long period of driving downhill, coupled with the high 30s outside air temperatures probably dropped the engine temp lower than what the computer expects, thus tripping the code. I had no driveability issues, engine warmed up normally on subsequent cold starts, and mileage was unaffected while the CEL was lit.
[/quote]

How many miles do you have?
[/quote]

A ok, thanks man, I am at 40,500miles so I have time.