Report: Check Engine Light/Trouble Code Due to Stuck Open Thermostat
Mazda 5 Problem
Average Mileage: 69,283 mi (36,500 mi - 101,000 mi)
Some vehicles may experience Check Engine Light illumination with a trouble code indicating the thermostat is stuck open. The thermostat will need to be replaced with a modified one and there is a software update for the Powertrain Control Module (PCM).
Visitor, 2006 Mazda 5, 56,000 mi
po126 engine code came up...insufficient coolant temperature for stable operation. Mazda shop said i need to change my coolant thermostat. They charge $100 bucks for the part, but you can find it for less than $50 at online stores.
Visitor, 2006 Mazda 5, 71,000 mi
Check Engine Light on - Code P0126
Visitor, 2007 Mazda 5
engine light on due to stuck open thermostat
Visitor, 2007 Mazda 5, 57,936 mi
Check engine light on and thermostat needed to be replaced
Visitor, 2008 Mazda 5, 63,000 mi
Car overheating. Check engine light on. Car doesnt overheat if interior vents are open at full blast. Called Mazda to find out if they plan on fixing this situation and they said "we cant help you car is out of warrenty". Too many people are having this same problem this is a manufacture problem please call Mazda and report it so they are aware. Mazda # 1800 222 5500. Even if you fixed problem call please.
Same problem, but the light goes on and off depending on the week- very annoying!
Visitor, 2006 Mazda 5, 75,400 mi
Check Engine light came on- code 126 a guy at pep boys recommended having the coolant thermostat replaced- payed $200 for parts + labor. the check engine light is off now so I guess problem solved?
I just found this website today.I had this problem too, last year... had it repaired. not too costly
I've been driving my mazda5 with the same code and will try to replace it soon.