Coolant temp.gauge pegged.new coolant sensor.I get 5 volts from connector.I am getting code po118 coolant temp. Sensor high input. Dont know what to check next?

P0118 - Engine Coolant Temperature (ECT) Circuit High Input Indicates the sensor signal is greater than Self-Test maximum. The ECT sensor maximum is 4.6 volts or -50°C (-46 °F). Note on some vehicles that are not equipped with an ECT sensor, CHT can be used and can set this DTC.

• Open circuit in harness
• Sensor signal short to power
• Damaged PCM
• Improper harness connection
• Damaged sensor

• Using signal simulation, disconnect sensor and simulate 1.0V on sensor signal circuit. Simulated 1.0V signal and scan PID voltage value should be similar. If voltage is similar check sensor, if voltage is not similar check related circuit and PCM

No , their arn't two coolant temp. sensors . One near the thermostat housing . The Temp sensor is a input to the PCM / ECM . The PCM / ECM needs the temp info for fuel calculations . The temp gauge on the instrument cluster gets this info over class 2 serial data network Hooking up a factory or professional scan tool that can read sensor data is the easy way to diagnose ,not guessing . Looking at factory service info. an wiring diagrams too see what is what is another way . You have no clue ,take it to a qualified repair shop.

The engine coolant temperature sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40°C/-40°F) while high temperature causes low resistance (70 ohms at 130°C/266°F).
The PCM supplies a 5 volt signal to the engine coolant temperature sensor through a resistor in the PCM and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. By measuring the voltage, the PCM calculates the engine coolant temperature. Engine coolant temperature affects most systems the PCM controls.
The scan tool displays engine coolant temperature in degrees. After engine startup, the temperature should rise steadily to about 90°C (194°F) then stabilize when thermostat opens. If the engine has not been run for several hours (overnight), the engine coolant temperature and intake air temperature displays should be close to each other. A hard fault in the engine coolant sensor circuit should set DTC P0117 or DTC P0118; an intermittent fault should set a DTC P1114 or P1115. The DTC Diagnostic Aids also contains a chart to check for sensor resistance values relative to temperature.
The ECT sensor also contains another circuit which is used to operate the engine coolant temperature gauge located in the instrument panel.

What make vehicle ? some vehicles have two coolant sensors . One for temp. gauge an another one for the ECM / PCM input. Do you have a check engine light lit ?

A DTC will be set if an abnormal reading occurs, P0116 for sensor performance, P0117 low input or

P0118 for a high input. The coolant temperature sensor temperature reading should closely match the

air charge/manifold temperature reading on a scan tool if the engine has not been run for over an hour.
The sensor circuit can be checked for proper voltage using a voltmeter.

here r your trouble code meanings:
1) p0123-throttle position sensor circuit, high input.
2)p0117-engine coolant temperature circuit, low input.
3)p0118-engine coolant temperature ciurcuit , high input.

If by ECS you are referring to the engine coolant temp sensor, the most common cause is that the coolant temp sensor goes bad and usually bias' towards the cold side of its sensing range which is around minus 40 degrees,(-40F). When this occurs the PCM had to over fuel to counter act the extreme cold in order to start the engine. But in normal temp areas this strategy just floods the engine. When the sensor is unplugged, the PCM substitutes the missing signal with a generic fail safe protocol which is preprogrammed. If the sensor is -40F, the vehicle just thinks its in Alaska, it doesn't know it has a bad sensor the PCM is just reacting to what the sensor is telling it. Its possible that either the wiring, or sensor connector has and open, short, or high resistance which may be the reason why replacing the sensor didn't work. Or maybe the wrong sensor was replaced, there should be two coolant temp sensors, one for the gauge, and one for the PCM. The PCM sensor is the one in question, to be honest, the PCM could be causing this as well, but at least you have a place to start.
I hope this info helps!~subyguru~

According to Autozone.com:

Because ECT (engine coolant temperature) sensor procedures vary depending upon their location, first locate the part. You may need to partially drain the engine coolant to prevent coolant spillage.

• Disconnect the negative battery cable.
• Unplug the ECT.
• Then, unscrew it.
• Reverse the removal procedures to install the new part.
• Connect the negative battery cable to the battery.

Related Parts:



Cooling Fan Switch
Content for class "spacer" Goes Here

Engine Temperature Sensor
Content for class "spacer" Goes Here

Temperature Switch
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Coolant Temperature Sensor

Fig. Remove the coolant temperature sensor
The coolant temperature gauge sensor is a temperature-variable resistor, or thermistor. As coolant temperature increases, the resistance of the sensor decreases or decreases, depending on the type of sensor.
A1 and A2 platforms use a different type of circuit that A3 vehicles. On A1 and A2 vehicles, the circuit is a "resistance to ground" type. A3 vehicles use a "variable voltage" type, where a voltage is supplied to the sensor. Because of the circuitry design on A3 vehicles, testing of the coolant temperature gauge is limited.
The engine coolant temperature gauge uses a heat sensitive sending unit to transmit an electrical signal to the gauge. The sending unit is a heat sensitive variable resistor that is located on or near to the cylinder head and threads into an engine coolant passage. The sensors are a Negative Temperature Coefficient (NTC) type. As the temperature increases, the electrical resistance of the sensor decreases. As the coolant temperature changes, so does the resistance of the sensor. The gauge is calibrated within the operating range of the sensor and interprets the resistance value to display the coolant temperature.
Beginning with model year 1994, the engine coolant gauge and the Engine Control Module (ECM) temperature sensors were combined into one sensor with 4 terminals. The basic operation remains the same in that their resistance decreases as the coolant temperature increases, however the actual resistance values of the 2 sensor circuits are different. The electrical connector of the 4-wire terminal sensor ( 1 and 2 ) is keyed to prevent improper connection of the sensor's electrical circuit.

Fig. Beginning with model year 1994, the Engine Coolant Temperature Sensors combined the sensors for the ECM and the gauge into one sensor-1997 2.8L V6 sensor shown

Fig. The electrical connector for the combined temperature sensors is keyed to avoid improperly connecting the sensor's wiring-1997 2.8L V6 connector shown

P0118 - Engine Coolant Temperature Circuit High Input

What does that mean?
The engine coolant temperature (ECT) sensor is a thermistor screwed into a coolant passage in the cylinder head. Sensor resistance is high when coolant temperature is low and resistance drops when coolant temperature increases. The powertrain control module (PCM) provides a 5 volt reference and a ground to the sensor. The PCM monitors voltage drop to determine coolant temperature. If the ECT reads less than freezing temp. when engine has been running for more than a few minutes, the PCM determines a circuit fault and sets this code. Or if the PCM determines the sensor resistance is out of specs, this code is set.

Symptoms of a P0118 could include:
* Very poor fuel economy
* A no start condition
* Vehicle may start, but run very poorly, blowing black smoke, running very rough and misfiring
* Illumination of MIL

Causes
A code P0118 may mean that one or more of the following has happened:
* A bad connection at the sensor
* An open in the ground circuit between the ECT sensor and the PCM
* A short in the voltage feed between the sensor and the PCM
* A bad PCM (less likely)
* A bad temperature sensor (shorted internally)

Possible Solutions
First, if you have access to a scan tool, check the reading of the coolant sensor. Does it read a logical number? If so, the problem is likely intermittent. Perform a "wiggle" test by wiggling the connector and harness to the sensor while watching the reading on the scan tool. Watch for any drop-outs. Drop-outs would indicate a bad connection. If the scan tool reads an illogical temperature, check the resistance of the temperature sensor. If it is out of specs, replace it. If it is in specifications, unplug the sensor and, using a fused jumper wire, jumper the two terminals of the connector together. The temperature reading should now be maxed out to above 250 degrees F. If not, there is likely a problem with the ground circuit or voltage supply.

Check for 5 volts reference voltage at the connector. Also check for ground presence at the connector. If you do not have 5V ref. and/or ground continuity, check for these back at the PCM connector. If you have these at the PCM connector, then repair open or short between the PCM and the sensor. If you do not, remove the offending wire from the PCM and then check for proper voltage at the PCM pin. If it's present now, repair short on the circuit. If it isn't present after removing the wire and checking the pin, replace PCM

NOTE: Usually, P0118 is indicative of a bad temperature sensor, but doesn't rule out these other possibilities. If you're unsure of how to diagnose a PCM, do not attempt.

Other engine coolant engine light codes: P0115, P0116, P0117, P0118, P0119, P0125, P0128

Hope helps.

It sounds like the coolant temperature sensor is beginning to fail. It is highly unlikely that the in-dash gauge is a problem. The coolant temp sensor inputs to the computer affecting everything from radiator fan speed, engine fuel/air calibration and a variety of other parameters.

Be absolutely certain to "burp" every bubble of atmosphere from the coolant system too. Air bubbles have the amazing ability to prevent coolant flow and will cause all sorts of problems, especially if the bubble wants to hang around the temperature sensor location.

Normal operating temperature is going to be around 210 F.

Most Autozone, Advance locations will read engine problem codes at no charge, so drop by one of those locations and let them read the problem code.

My guess will be the coolant temperature sensor. Then have the problem code reset, remove all air from the coolant and let us know how this worked.

I have about 15 years experience with Audi/VW. The coolant issue is more like the result of the ECM coolant temp sensor failure. The Cat code might be the front oxygen sensor on that bank and not the front cat. If you need more information about this repair please fell free to contact me at [email protected], I have over 30 years of automotive experience to assist you, thanks.

If you changed the coolant temperature sensor and it had a 5 volt ref signal to it then you replaced the wrong part. You need to replace the coolant temperature sending unit.  The coolant temp "sensor" is an input to the ECM for your fuel injection system. The coolant temp "sending unit" is for coolant temp reading at the gauge, It is an NTC switch (negative temperature coefficient) which means as temp increases/resistance decreases.