Why is P0128 still around after changing thermo?

Tim Cross

Asked by Jun 17, 2015 at 01:35 PM about the 2007 Mazda MAZDA3 s Touring Hatchback

Question type: Maintenance & Repair

Hey guys I'm a 2007 Mazda3 Hatchback owner looking for some help with a trouble
code. Hope you guys can solve my problem.

I had codes P0126 and P0128 pop up. I like to do work myself to save money so I did
my research and after diagnosing the problem, I realized I need to replace the
Thermostat and the Engine Coolant Temperature Sensor.

After proper installation, P0126 went away, but P0128 stuck around. I thought it might
just need to be cleared so I cleared the code myself, only to find it kept popping back
up. So I took it to my neighborhood mechanic and he told me that the monitors had to
be reset at a Mazda dealer.

The other day I took it to the Mazda dealer and they reset the monitors which cleared
the trouble code... until about 45 miles later the code came back.

I have run diagnostics to see if the engine is reaching the correct temp. After 5-10
minutes of idol I am reading 170-190 degrees near the place where the engine meets
the thermostat and about 205 degrees at the top of the engine.

I'm truly stuck here and late on my smog check for my vehicle registration. Any help
would be appreciated, thank you!

1 Answer

Tom Demyan


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