Check Engine Light Suddenly Appears

[mbagrad]

I have a 2006 Mazda 6speed. On the way back from Las Vegas to Orange County, CA my check engine light suddenly appeared. Before I left for Las Vegas I had the car checked out by a reputable mechanic who assured me that the car was fine. The drive was around 4 to five hours each way.

I had this same check engine light issue (without the long drive involved) when I first bought the car where I was told that there was residue under the hood that caused the problem. The dealership that I bought it from fixed it at no charge. This was about three months ago and it has happened again.

I had it scanned and the code that came up is P0126 (low coolant temp) so I asked someone at an autoparts store for advice and he topped off the coolant reservoir and told me to monitor it that it could be a coolant leak.

I've read on the Internet from others who have had this issue and thay wrote that their thermostat was "stuck open" but I don't know what that means.

I hope someone can help me with this and thank you in advance.

 

[batou079]

aka possible bad thermostat. you need to take it in and specifically ask them to check that issue.

 

[Steve04s]

I know this is old, but i never read anyone who had a concrete answer on the fix.
i have thrown this code last week and cleared it and it stayed off so far. i was noticing the temp gauge was not climbing to the halfway mark where it should be, but more of a 1/3 way up. Changed the Tstat 4 months ago, so i guess it could be a faulty one and changed it again last nite. Idled for 20 minutes, temps are perfect...until i start driving, they start dipping to about the 1/4 mark on the guage! WTF with a brand new Tstat (195*), still no fix? no codes are thrown yet though. what can it be? maybe it needs to be burped more?

Car is a 2004 Mazda6s 3.0

 

[m.o.b.s.]

I'm having an issue too, but on my Mazda3.

Car sits overnight. Key turned to ACC and gauges begin to read. Coolant temp rises to normal/warmed up before it even starts. It's a little tough to start cold, but starts fine when warmed up. Under acceleration the needle goes down. Let off then returns to normal. I have the P0126 code. I replaced the thermostat last month due to a singular overheating incident. Trouble free til now...?