How to test a faulty engine coolant temperature sensor ECT fault codes P0118 P0115 P0116 P0117 P0119
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- Опубликовано: 2 окт 2024
- How to test an engine coolant temperature sensor with a voltmeter and what readings should you get? What does fault code P0118 mean? How to fix fault code P0115? How to check the resistance of a sensor. What is a NTC sensor? How to check the voltage of a sensor?
The Engine Coolant Temperature ECT sensor is a variable resistor or thermistor. It’s an NTC Negative Temperature Coefficient thermistor where, as the temperature increases, it’s resistance decreases.
An ECT sensor is connected to the main computer (powertrain control module PCM or Engine control module ECM or Engine Control Unit ECU). The PCM supplies a reference voltage (typically 5 Volt) and constantly monitors the ECT sensor signal. Based on this signal, the PCM adjusts the engine performance and operates the electric radiator fans when the temperature reaches a pre-determined level.
If the signal from the sensor is missing, or it is outside of the expected range, the PCM turns on the Check Engine light and stores the related trouble code in its memory.
Ways to test the engine coolant temperature sensor
Because the tip of the sensor has to be immersed in coolant, the low coolant level or air pockets inside the cooling system can cause the signal from the sensor to be incorrect. The coolant level always has to be checked first when dealing with cooling system problems. The ECT sensor connector must be checked for damaged pins or corrosion.
Testing the ECT/CHT sensor Resistance: One way is to measure the resistance of the sensor at different engine temperatures and compare the readings to the specifications listed in the service manual.
Measuring the resistance of the Engine coolant temperature (ECT) sensor. The resistance of the sensor can only be measured when the sensor is disconnected from the circuit. The reason is that if you measure the resistance of any electrical component that is still connected to the circuit, the measurement won't be accurate.
The resistance when the engine is cold is about 2,953 Ohm
It drops to 248.5 Ohm after the engine had been fully warmed up.
The resistance specs vary depending on the car.
Checking the ECT/CHT sensor Voltage: Another way to test the sensor is to measure the voltage across the sensor terminals with the ignition on. Measuring the voltage of the engine coolant temperature (ECT) sensor. Checking the ECT sensor voltage. The sensor is connected to the engine computer (PCM). The PCM supplies the reference voltage (typically 5 Volt); another wire is the sensor ground. Both the reference voltage and the ground must be checked first. Since the resistance of the sensor drops as the engine warms up, the voltage drops too.
When the car is cold, 3.96 Volt is an average reading. On a fully warmed up engine the voltage drops to around 0.988 Volt. With the sensor disconnected, the multimeter will show 5 Volt. If there is no voltage, you know that the circuit is either open or shorted to ground. For example, one of the wires in the sensor harness could break or rub against a metal part and short out.
An example of another sensor that measures the temperature is the intake air temperature (IAT) sensor. Readings of the IAT and ECT sensors when the engine is cold. If the car has been parked overnight, the temperature of the engine (ECT or CHT) and the temperature of the IAT sensor located in the intake should be very close.
Diagnosing intermittent temperature sensor problems: If there is an intermittent problem in the ECT or CHT sensor circuit, you can use a scan tool to diagnose it.
Intermittent fault in the ECT circuit. With the scan tool connected, you can monitor the sensor voltage while tapping lightly on the sensor and wiggling the harness and connector. A change in voltage indicates the problem area. Another way is to monitor the ECT temperature.
Disconnecting the ECT sensor will show as -40 degrees on the scan tool.
Why does the ECT sensor show -40°F (-40°C)?: When the ECT sensor is disconnected, the scan tool will show -40 degrees (-40° Fahrenheit equals -40° Celsius). This feature is useful when diagnosing trouble codes related to the ECT sensor. When the PCM sets the trouble code, it also stores the freeze frame which is a snapshot of major parameters at the time of the fault. If the freeze frame shows the ECT at -40 degrees, it means that the ECT sensor circuit was open at the time of the fault. It could be a problem with the sensor itself, connector or the wiring harness.
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Brilliant lesson! I have been trying to solve the problem with my Merc.Vito for three years. It cost me a lot of money and no one solved my problem! Even worse than that, I had to replace the engine due to overheating! Watching this video, it is completely clear to me that my problem is in the wires from the sensor to the computer. Thank you very much, I'm going under the car in the morning!🥰
Thanks for the comment, hope you find the issue quickly 🙏🏽
Thank you great analysis.
If the check engine light goes away, comes back after a while what could it possibly be?
Probably an intermittent fault, sensor on its way out. Or an issue with the wiring, loose connection, water/corrosion.
@GarageTechAutomotive sorry I meant to add that I have a P0118, I had it initially maybe a year or so ago, I replaced the ect sensor, got rid of that but just came up again maybe 2 weeks ago.
Going to assume the part itself shouldn't go out that fast and check the wiring...
Would a faulty temp sensor cause erratic fuel injection? My foot will be on the accelerator and the engine will just drop in power for a split second then power back it will do that a bunch of times at different times while driving the vehicle
There are so many different sensors to calculate engine load while driving so the ECM knows how much fuel the engine needs. You need a mechanic or at least an OBD scanner.
Hello mate!
Thanks for offering us such knowledge for free and so well put together.
I'm planning to buy a 987.2 3.4 with the pdk gearbox. With around 150k miles.
Here in France E85 (ethanol fuel) is very very much cheaper and converting the car is one of the first mod I plan to do. It's quite a sensitive subject for Porsche enthusiasts here but I've been confirmed that thanks to the direct injection it's not problematic it's better to change the spark plugs for iridium's though.
Do you have any information about that? Apart from that, no mods planned as it has been serviced recently (gearbox oil change/water pump and belt).
Thank for your time mate.
Take care.
Marc
Hey Marc, thanks for the comment, unfortunately I don’t have any info on E85 and conversions, seems like ethanol blended fuel is becoming more popular so I’m sure there’s some info somewhere. Good luck 🤞🏼
Brilliantly explained mate.
Brilliant, really interesting and put over in a really relaxed manor thanks 👍🏼👍🏼👍🏼👍🏼👍🏼
Thank you 🙏🏽
Hello I have audi a4 1.6 my fan works all the time as soon as i turn on the car it starts and doesn't turn off only when the car turns off it turns off what's the problem please get me this code ( p0116 Engine coolant temperature (ECT) sensor - range/performance problem ) I have changed the two temperature sensors
@@elison25 hey, if you have changed the coolant/engine temp sensor and the radiator sensor, then I would check the wiring to make sure that it’s all ok. Is the temperature gauge or information on the dash working correctly. Do you have AC, if that’s on or if there’s an issue it will keep the fans running.
@@GarageTechAutomotive good morning temeratur stay in order 90c the AC I don't turn it on because it doesn't work, I've had it off for months today he also issued me this code
ERROR CODE: P1292
Engine cooling thermostat
@@elison25 if both sensors have been changed then you need to check the wiring and plug pins etc. P1292 is a short circuit fault meaning either the wires are connected to each other, corrosion in the plug possibly, or a faulty sensor
@@GarageTechAutomotive you don't think it should be changed cooling thermostat
@@elison25 is it the electronic controlled thermostat?
I have a p0118 on my audi B7. The plug back there that connects into the gray sensor is missing. Not intact with the prongs. I only have the pinkish rubber on the prongs that holds them in the connector. My question is how do i knw its the sensor or a short or open wiring ? Sensor nd o ring was corroded I shld add but wen checking the prongs with a ligh voltage indicator .light does not light up. So how wld i further my daignose for now ? Shld i open all the rubbers to check wires to ecu or to bottom sensor or ? Pls help.
Hey, sounds like you need to replace the plug and terminals and some of the wiring until no more corrosion is visible. Any corrosion can effect the signal and a broken connector will give you a fault every time the engine moves. You’ll need to check to make sure there’s no corrosion in the sensor pins to, otherwise the sensor will need replacing too.
I've been looking for a replacement temperature sensor for my bike for 2 months. At this point it seems my only option is to scrap the whole bike because it won't run properly without it.
Every illustration you did is such amazing ,you are brilliant man.
Thank you 🙏🏽
Thank you for the insights
Found your channel whilst trying to learn and understand coolant temp sensors because my 14 Mazda cx-5 2.5 shows on my scan tool that the thermostat monitor engine coolant temp PID is -40F all the time even though both the primary and secondary coolant temp sensors read the same and are accurately reporting according to my tests that I got from Mazda's factory service manual.
I don't understand how this can be the case. It isn't throwing any codes. The temp sensors change properly as temp goes up or down. Also, my fuel pulse width is showing out of range as well. It's showing 1.4-2.1 when the scan tool says the range should be 0-0.1s. don't know why that is, either.
what about a P0597 (open circuit)- I've replaced the thermostat and sensor, still getting the error (Kia Stinger GT2). Bought a Ancel Probe and just don't know where to look or how to test.
Hey, P0597 is linked to the thermostat as you have mentioned, if you’ve replaced the thermostat and sensor, you really need to check the wiring. You would be best to try and get a wiring diagram, and check for a feed and earth. Open circuit fault would indicate a broken wire, check the connector terminals etc. I would strongly recommend not to use a power probe, you could easily send voltage or earth a circuit that isn’t meant to be, and either blow a fuse or worst fry the ECU.
@@GarageTechAutomotive - I did what you described (got the wiring diagram) and it was 4.76 volts at the ECU, 0.0 volts at the sensor, so I'm guessing the power wire is broken... this sucks because the wiring is in such a ridiculously hard place to get at (between the firewall and the engine with about 3" or less to maneuver my hands. So I guess my next move is to figure out how to remove the wiring harness so I can take it off and examine it. Any suggestions??
@@blacktopmods hey, I’d run an overlay piece of wire from the ECU to the sensor first, just to double confirm that the original wire is broken. You could leave that in place as a temporary fix, but you’ll need to find where the original wire is broken, as over time, other wires may break or already be damaged and corrosion or short circuits could occur.
Great video information ❤
Hello, my car is a fiat bravo 2 2008 1.6 multijet diesel. Since I have it from the last summer the car does not have a stable idle. In the winter that problem was gone. This summer it is here again. I tried a lot of things but nothing is helping. Now I have error codes P01EA and P0487(for EGR). P01EA looks like very generic code but it looks like the ones for engine coolant problems. So I am thinking is it possible for a faulty coolant temperature sensor to cause an unstable idle when the car is warming and hot? For example, maybe the coolant temperature sensor is sending wrong information to the ECU that the car is still cold and the ECU is pushing the wrong air-fuel mixture as if the car is cold? Thanks in advance!
Very good clip
I've replaced my coolant sensor with a oem one and I still get codes po118 po117 and I've checked wiring and sensor is perfect my truck stalls and throws those codes and replaced pcm 2 times
I’d definitely check the wiring and connecters again as getting both codes for open and short circuit is strange, make sure there’s no corrosion in the connecter. Also check your earth points for the PCM etc.
@GarageTech it don't make sense I've been over wiring even replaced wiring and pcms and connectors and grounds are perfect
@@twinscrew9.047 ok wow this is a strange one, do you have a full wiring diagram, I’d check to make sure there’s no shared earth wires etc on the same circuit, another faulty sensors or actuator could cause a fault on the coolant circuit. There must be something causing it to stall, faulty injector, crank or camshaft sensor, a faulty coolant temp sensor wouldn’t usual make if stall, just run rough.
@GarageTech it's on it's own circuit own ground
Hi Darren excellent video very helpful. I wondering if I give me some advice. The 4 pin temperature sensor does it control the fans on a audi 1.8t 20v. My fans come on at the correct temperature but it just starts and then stop. Check all the wires from ecu to sensor and they are fine I also replace the sensor. Please please your help will be appreciated. Thanks
Hey Jason, from memory I think there’s a separate temp sensor for the rad fans in the radiator, if you’ve got some wiring diagrams you can check, I’d have a look at that and I think there’s a rad fan relay control module, normally somewhere down by the left chassis leg under the battery. Probably that’s the issue
@@GarageTechAutomotive HI it has a fan control module in the fans and the plug to the fans have 4 wires 1 comes from the positive and the other one comes from negative of the battery. Then two thin wires one comes from a relay which gives 12v when the ignition is on and the other one comes from ecu. I have been trying to get it right but no luck.
@@jasonbarry8104 oh ok, if you’ve check all the wires I would suspect it’s the fan control module, have you had that replaced?
@@GarageTechAutomotive HI no I have not replace it. When I unplug the 4 pin the fans start working.
Thank you very much. Very detailed and clear explanations.
I just got a P0116 code and my mechanic is away til the end of the holiday weekend? Can I drive it until he comes back or is it undrivable?
Hey, the car will run on a default map, not the best condition to use the car for a long period or for a long trip but will be ok until the weekend. I’d get it sorted as soon as you can and minimise any unnecessary trips.
Hi, appreciate your informative lecture. Really cool. My problem is, with key on, i don't have 5V but 0.005V, when engine is running i get 13.75V which is the alternatir.
Where to from here. Thanks in advance.
Are u sure you are on the right sensor.
thank you for the very instructive video
Where is your workshop located?
Hi @ 9:05 can i use the paper clip on the plug method to test if the fans are working or will that ruin the computer?
Hey, it will just cause a fault as the circuit will see 0V, short to earth, circuit too low. Depending on the engine etc it may put the coolant fans on full speed as a default. If the engine has a radiator temp sensor too, it may use that as a default so may not necessarily put the coolant fans on.
@@GarageTechAutomotive Thanks. Ya i am thinking of trying this for my 2008 civic it has a coolant temp sensor. My concern was on the forms for 2008 civic I cam across this message.
The car does not use a coolant temp switch to run the radiator fan, it is controlled by a temp sensor now. Shorting wires for a sensor can ruin the computer.
Google searching the below will show the full thread
"re: 2008 civic cooling fan wont work"
I just don't want to ruin the computer
@@Random.Adventures. best not to short anything if you’re not sure. What’s the issue anyway, are the coolant fans not working?
@@GarageTechAutomotive the issue is I have a 08 civic and I just never hear the rad fan come on. Last week i ran my car for 40 mins and sill no rad fan. If i turn on my ac then both fans will kick in. So I figure it could be the coolant temp sensor at the bottom of the rad. In about 25 mins the top coolant hose is hot and the bottom one is cold but shortly after both are hot so I believe the thermostat is working
@@Random.Adventures. what is the temperature gauge reading, if it’s staying at around 90c after 40mins I’d say that’s normal, just means the fans don’t need to be on, and the system is working efficiently without them. if the temperatures rising to like +110c and the fans haven’t kicked in then yes you’ll need to look into it.
I had a p0116 about a year ago and changed the ect sensor for a genuine one, along with a genuinethermostat, and also sorted to water pump. Now pretty much exactly 1 year later im getting a p0117. The code comes back instantly once I clear it. Does this point more towards the wiring side of things?? Surly the life span of the sensor is longer than a year. I'm useless with wires is all 😅
Hey thanks for the comments, are you getting any reading on the temperature gauge? A P0117 normal means a shot to earth so the sensor could be faulty, you would need to check the resistance valve, for this fault code it would have a very low valve, near 0ohms. Otherwise yes a wiring fault shorting to earth, the wires could be shorting to each other. Good luck, let me know what you find 👍🏼
@@GarageTechAutomotive I have the torque app and when I start the car first thing on a morning (dead cold) it reads higher than the ait, and when I unplug the ect sensor the coolant drops to -40. The wiring harness and the terminal look as sound as they should for the age of the car (2003 audi tt) so I'm suspecting it's the coolant temperature sensor 🤔 I've recently been informed that just because they say "genuine" on ebay, doesn't always mean they are aha ot was about £25 at the time. I think ill get one direct from audi and go from there since that would be the easiest fix for me. Do you know the part number for the coolant temperature sensor on a mk1 tt by any chance?
@@shaunprince6986 those sensors on the early VWG cars were a common problem, is it the 4 pin green one? It has 2 sensor in it, one for the dash (G2) and one for the engine (G62) does your fault code reader give you the sensor code name I.e. G62 or G2. At least that will give you a clue to which circuit it is. Anyway, the part number used to be 55919501A but that may have changed. Best thing to do is ring your local Audi centre, even a VW garage will be able to supply you one. In the uk you’ll also get 2 years parts warranty. Worth it in the long run 👍🏼
@@GarageTechAutomotive Yes, its the 4 pin green one and unfortunately it doesn't say anywhere about a G2 or anything :/ ill change the sensor and go from there. I'm not a mechanic but am fairly mechanically minded. Just not with wires so that's my last resort. If a new sensor doesn't do anything ill get an auto electrician in. Thank you for all your help 🙏
Wow this explanation is brilliant!! I really appreciate all of the effort... Too bad I still have issues figuring out what i have to do with my varying P0115/P0117 codes (right now P0117 with -40deg)... I have got a Mini with a MAP controlled thermostat, so I have got 4 wires coming together to a single plug (2 for the MAP heating element and 2 for the coolant sensor). I have done a quick multimeter test that shows [pin1:12V], [pin2:3.5V], [pin3:0V], [pin4:5v]. I have got the electrical diagram that states pin1&2 are a couple (2=ground) and pin3&4 are a couple (3=ground). I dont know which of the couples is the MAP and which is the coolant temp sensor since i don't understand the difference of the diagram's symbols. I really could use some help since my garage doesn't know what they are doing (replaced thermostat 3 times!). A BWM/Mini specialist garage that i asked told me he wanted to help by replacing the thermostat for a original thermostat (of which i have my doubts). I am an engineer, so i have technological knowledge, but I have never worked on cars and electrical components....
Hey thanks for the comments, if you do a search for a variable resistor symbol, normally a rectangle with an arrow through it, that might help identify which circuit is which.
Thank you for your video! Having issues with my A/C. Come to find out that my fans are not turning on. Thought it was the sensor or the fans. I bypassed the system and fans work. Changed temp sensor. Still not working. Tested the voltage from watching your video. And I have 5 volts from the main and 0.001 from the ground. Not sure where to go from here. Any suggestions? TIA
Code was the P0118
Could the new sensor be bad?