Thermostat replacement

Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car.

https://www.2carpros.com/articles/replace-thermostat

Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

If air cleaner duct work in the way remove it. Then remove two bolts from housing an dcleand surfaces then reverse procedure for install. The bottom bolt in pic ned only be loosened until you can remove by hand, use a universal socket. 13mm

That code is for a misfire No1 cylinder, check that the lead is secure and the spark plug is ok, its probably something simple after doing the tune, if you still have a problem, post back and we can work through it.

Check for vacuum leak around that cyl, swap spark plug to another cyl to see if the fault moves to that cylinder, it will be something to do with air fuel spark or compression at that cylinder.

Sounds as if it is a head problem, you will have to get the head off and get it crack tested and checked for bend, do you have the equipment to do this work?

CIRCUIT DESCRIPTION
An Engine Coolant Temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the Powertrain Control Module (PCM) for engine control and as an enabling criteria for some diagnostics.

The air flow coming into the engine is accumulated and used to determine if the engine has been driven within conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach regulating temperature of the thermostat, diagnostics that use engine coolant temperature as enabling criteria, may not run when expected.

If engine coolant fails to reach a preset target temperature before a calculated air flow is accumulated, DTC P0128 will set.

CONDITIONS FOR RUNNING THE DTC

* This Diagnostic Trouble Code (DTC) will only run once per ignition cycle within enabling conditions.
* DTCs P0112, P0113, P0117, P0118, P1111, P1112, P1114, or P1115 are not set.
* Coolant temperature is more than 40 °C (-40 °F).
* Coolant temperature is less than 78 °C (172 °F).
* Air temperature is more than -7 °C (19 °F).
* Engine running more than 2 minutes and less than 30 minutes.
* Vehicle speed is more than 24 km/h (15 mph) for more than one mile.
* Mass air flow average reading more than 15 g/s.

CONDITIONS FOR SETTING THE DTC
The length of time for the engine coolant to reach a preset temperature has been exceeded.

ACTION TAKEN WHEN THE DTC SETS

* The control module illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC

* The control module turns OFF the Malfunction Indicator Lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Use a scan tool in order to clear the MIL and the DTC.

DIAGNOSTIC AIDS

* DTC P0128 is designed to detect a faulty thermostat.
* It is possible for a skewed ECT sensor to cause a DTC P0128 to set.
* If a DTC P0125 and DTC P0128 are both set, a skewed ECT sensor is the most likely cause.
* A skewed IAT sensor may cause this DTC to set. The IAT sensor should read near ambient temperature with the engine running.
It could be a bad coolant temp sensor or a bad inlet air temp sensor but is most likely a bad thermostat.

See pictures, you have to go through the wheel well to reach it.

Sounds like a tstat problem, like maybe not working at all especially if it does htis within the first few minutes of start up. Otherwise check for a bd head gasket

So coolant boils over the cap?Also is the upper and lower radiator hoses getting too hot to hold?

The thermostat is located on the tube headed to the water pump. Here is a guide and a diagrams (Below) of how to do the job

https://www.2carpros.com/articles/replace-thermostat

Here is your car (below)