Check Engine code P0128

The Check Engine light is on with the code P0128 for the coolant thermostat (coolant temperature below thermostat regulating temperature).
Experienced mechanics share their insights in answering this question :
The cooling system temperature is regulated by thermostat, and the cooling fans order to keep it at optimal temperature for the motor to operate. It does this by keeping the thermostat closed and the fans off until the coolant reaches around 195 to 210 degrees then opens the thermostat to cycle the coolant through the radiator while the cooling fans blow through the radiator cooling the coolant. If the thermostat is stuck open then coolant will never stay inside the motor long enough to heat up to the specified temperature. This would set a P0128. To verify that the thermostat has failed a proper inspection of the Check Engine Light should be called out by a qualified technician, like the one from YourMechanic.

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Error code P0128 indicates that your engine coolant temperature is below the thermostat regulating temperature. This means that your Engine Control Module (ECM) or Powertrain Control Module (PCM) has recognized that your engine is running cooler than it`s supposed to.
P0126 is either replace coolant temperature sensor or replace the thermostat. According to my research, 99% of the people who had this code needed to replace the thermostat. Once that was replaced, 99% of the people said that the light turned off and that they noticed the car ran better than it did before.
The P0126 code meaning is “Insufficient Coolant Temperature for Stable Operation.” This is telling us the car is reading a coolant temperature that is below… The cooling system temperature is regulated by thermostat, and the cooling fans order to keep it at optimal temperature for the motor to operate.
Low engine coolant can alter the engine running temperature enough to signal trouble code P0128. Your intake air temperature sensor, coolant temperature sensor and coolant fan could also signal this trouble code, so these should be inspected after you look over your thermostat and coolant level.
Depending on the root cause of the issue, the costs of fixing the code P0128 will most likely range from $150-$250.
The P0217 code means that the engine is or was overheating and should be turned off as soon as possible.
How long can I drive with this issue? As we mentioned earlier, since this is not a serious issue, you can drive your car indefinitely. It won`t make your car stop all of a sudden. You can comfortably drive with this issue.
The P0118 code refers to issues with the Engine Coolant Temperature (ECT) circuit and its accompanying sensor. The ECT is a thermistor, or an electrical resistor, whose resistance is significantly reduced by heating. The ECT is located in the coolant passage in your engine`s cylinder head.
A faulty sensor can cause the fuel mixture to adjust. This causes the engine to shake or vibrate when the vehicle is at low speed and can even bring about strange behaviors, power losses, etc. Engines are highly sensitive, especially to inappropriate air-fuel mixtures at idle.
The Coolant Temperature Sensor is used to measure the temperature of the engine coolant. The readings from this sensor are then fed back to the engine control unit (ECU). This data from the sensor is then used to adjust the fuel injection and ignition timing.
Coolant Leaks

Oftentimes when the thermostat fails, it remains in its closed position. As the engine overheats, coolant will overflow out of the thermostat housing. This means that coolant leaking out of your engine could be a sign that your thermostat has gone bad.

Reconnect the sensor to the wiring and replace the missing coolant to the required level. After doing this, delete the fault code from the ECU using your OBD II scanner and take the car for a test drive. Replacing these parts will most likely fix the P0128 code issue on your car.
Generally, repairing a thermostat costs around $200 to $500. This is the price range you`ll find for most vehicles, although some may be higher or lower depending on the circumstances. But if we`re talking complete replacement, expect the price to increase by $50.
Reconnect the sensor to the wiring and replace the missing coolant to the required level. After doing this, delete the fault code from the ECU using your OBD II scanner and take the car for a test drive. Replacing these parts will most likely fix the P0128 code issue on your car.
Where Is the Engine Coolant Temperature Sensor Located? The ECT sensor is typically near the thermostat in the cylinder head or thermostat housing. The ECT sensor is typically near the thermostat in the cylinder head or thermostat housing.
The thermostat may not function properly and may result in Diagnostic Trouble Codes P0128 or P2181. To correct this condition, follow the procedure outlined in this bulletin to replace the thermostat and air bleed the cooling system after refilling. No drivability issues are associated with this condition.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Service engine warning, MAF code and O2 sensor code, along with check suspension light are turned on
ANSWER : Hello, it sounds like you have quite a few things going on. I am going to do my best to break them down for you.

First if the engine is very loud when idling and the belt has already been replaced, there may be an issue with the tensioner or idler pulley.
Next, the Navigator is known for needing service to the air suspension system as it gets up in miles, the most common causes of these are the air struts themselves have failed, or one of the air lines has a leak.
Lastly, if the O2 sensor and MAF are continually coming back after the sensors have been replaced, the most common cause would be either an exhaust leak or a vacuum leak.

Qualified technicians such as the ones at YourMechanic will be able to diagnose these issues and recommend the best path to repair, starting with a diagnosis of your warning lights.

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Check Engine light on. Would the computer give all error codes in one shot? How do we know the engine’s condition?
ANSWER : Hi there. From the description you have provided, I’m am inclined to agree with your assessment of a used engine being installed in your vehicle. An inspection of the engine, by a qualified technician could determine whether the engine is sound. The Check Engine Light on and having a TPS (throttle position sensor) code does not necessarily mean the sensor is at fault. Circuit tests should be performed to confirm the fault. The likelihood of the ECM (electronic control module/computer) giving you all the codes at once is remote. Other component failures could occur. Address those as they come up. Even though you already made the purchase, I recommend having your vehicle inspected by a certified technician so that you can get a thorough evaluation of the car’s true condition.

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P2196 OBD-II Trouble Code. came and went in 24 hours. 4 starts.
ANSWER : If the mechanic tested the output (functioning) of the oxygen sensor, especially according to the protocol at this link and found that the sensor was non functioning at that time, what you might be experiencing is a "failing" oxygen sensor and so the latest instance of Code P2196 might be explained by that. A complexity though is Code P2196 has many causes other than a failing oxygen sensor including: a faulty fuel pressure regulator; MAF (Mass Air Flow) sensor; ECT(Engine Coolant Temperature) sensor or damaged ECT wiring; leaking or stuck open fuel injector or injectors; and spark plugs and/or coil pack. Basically, if the Code (P2196) recurs, the oxygen sensor output can be re-tested but the mechanic will hopefully be aware of all these other possible causes of that Code setting. If the Code recurs, you can request a check engine light diagnostic and a certified Mechanic, dispatched by YourMechanic right to your location, will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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check engine light O2 sensor already replaced same codes still popping up after replacing old O2 sensor
ANSWER : Hi there. What you received from the parts store was a code retrieval, not a diagnostic. The codes are set when a fault is detected against normal operating parameter. The computer does not know what caused the fault, only that the fault meets the criteria for this code to set. There could be a problem in the wire harness, converter, or the ECM. The code and data are needed to properly assess the direction that a diagnosis needs. I strongly suggest having a qualified technician perform an inspection to avoid replacing unnecessary parts. Your Mechanic has several available technicians that can assist you with a check engine light inspection.

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p0011 code,check engine light one, changed bank 1 vvt solenoid and check engine light still on?
ANSWER : The P0011 code is typically caused by oil issues with the car. I would particularly make sure the engine oil level is not low. The VVT solenoid relies on proper oil levels to do their job. If they don’t have enough oil, they won’t work. You can have a mobile technician from YourMechanic visit your home or office to inspect the Check Engine Light for you. If you follow through with a repair with us you will be reimbursed for the cost of inspection.

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I have a 2007 dodge ram 1500. Check engine light was on code came up as alternator. Replaced it and the check engine light is stil
ANSWER : Hi there. When an error code is created, it is often stored in the ECU until it is cleared by a professional mechanic during a check engine light inspection. It is possible that this is the source of your error light, especially if you are not having any further problems starting your vehicle.

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Check engine light with a code about insufficient temperature P0126 to the engine.
ANSWER : Hi there. The coolant temperature sensor (CTS) is not working correctly. The sensor is sending a signal that the engine is already warm and when the engine first starts up, it needs more fuel a rich mixture to produce more heat until the engine is hot. When the engine is hot, the fuel backs off making the fuel trend more lean. I recommend replacing the coolant temperature sensor. If you need further assistance troubleshooting your cooling system, then seek out a technician, such as one from YourMechanic, that can assist you with your vehicle.

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O2 sensors changed, but check engine light still showing code after clearing it I checked fuse. Wires are good and used Denso OE.
ANSWER : Depending on what the code was for will determine if the oxygen sensor was to be replaced. If the conditions were for a rich or lean mixture and it said oxygen sensor, then the spark plugs and wires could need replaced if its a rich reading or the fuel injectors could be clogged or not working if its a lean mixture. If the code said that the oxygen sensor was bad, then check the harness and see if there is a break in the wiring or a short to ground in the wiring from the oxygen sensor to the main harness. If you need further assistance with your check engine light being on, then seek out a professional, such as one from Your Mechanic, to help you.

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