What do i need to do to fix this problem
Check your temperature sending unit and be sure it is working properly and then check to see that your thermostat is working properly if you are getting heat inside of the vehicle from the heater then this would be a good indication that your thermostat is working properly. also check your coolant level is correct.
code P0128 is coolant thermostat ( coolant temp below thermostat regulating temperature )
SOURCE: how do i fix the check engine light code p0128 on
May be a faulty thermostat or the thermostat sensor. Change the thermostat first it's a lot cheaper, unplug the neg battery terminal for 10 minutes to allow the code to erase and check it again. Good luck
SOURCE: What can keep causing Check engine code P0128
P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature.)
Meaning the regulating temperature is higher than the themostat cooling temperature . you may have to replace the Coolant sensor again. or maybe both. Sorry !
SOURCE: check engine light on got
P0128 ECT Sensor Below Thermostat Regulating Temperature
P0420 Catalyst System Bank 1 Low Efficiency
P0455 EVAP System Large Leak (0.080") Detected
For the 'P0128' your engine isn't getting up to operating temerature. This could be because of a low coolant level or your thermostat is stuck open. For 'P0420', this indicates your catalyst isn't working as well as it should. If you have a four cylinder, this will be the first cat in the system, if you have a V6, then it will be the one on the driver side. Since this code can also indicate a clogged catalyst, you should get this checked at an exhaust shop. They can do a back pressure test to see if it is clogged. For the 'P0455', this indicates you have a fuel leak from the pressure system in the fuel tank. The EVAP takes fuel from the tank that builds up pressure and stores it in a canister until you start the engine. Then it shunts this fuel into the engine to be burned.
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how did you determine that you had code P0128 ? did you take it to a shop, or did you get this yourself from a specific procedure to view engine codes. I am trying to figure out how to read check engine codes on my 2005 grand cherokee
I have an 05 grand cherokee with the same code. Coolant level good. Changed the thermostat because it is the cheapest swap. still ran cool on guage. Changed coolant temperature sensor, engine at proper temp on guage ( it is located on the front top center of engine in front of the plastic runners for the intake). No more P1028 code. Drivability problems now. Changed spark plugs approx. 54000 miles. The old plugs were badly burned down to 65 thousandths. New at plugs at 44 thousandths. More power but still have drivabilty issues. Still trying to find out why? I think 1 or more of the 4 oxygen sensors are bad? Maybe converter damaged? Hope this helps Derek
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