Engine Coolant Temperature Sensor P0117 / P0118 | How to Test and Replace

Now in most cases when a car comes into the shop and it has an ECT circuit high, your first indication is more than likely that sensor is going to be unplugged or it's missing a ground. Stop worrying about swapping parts instead let me show you how to re-scan tool data so you can properly diagnose any car that comes into the shop. Let's take a look. What's up guys Oscar Gomez here from Master Automotive Training. Hey if you haven't done so already give us a like and a follow and make sure you turn on that notification bell so you get a ding every time we drop a new video. So don't worry about swapping parts make sure you guys stick around so I can show you how to read scan tool data to help you much quickly figure out what's going on with the car. Shout outs to our buddies at Autofix for the D1 light that we're going to test out today on this problem that I induced and you guys are going to stick around and figure out what I caused on this particular car. If you're trying to pick up your own Autofix and you guys like the information you're going to see today make sure you check out my link in the bio that also has a discount code so you can pick up your own D1 light. Let's get ready and let's take a look. Alright guys so let's go ahead and jump right into this as you guys already know for me I always start with EOBD first so we're going to click on EOBD and now the tool is doing its thing it's talking to the dongle which I already put into the DLC. Now if you guys I've talked about this before but if you're not aware these are all the communication protocols that exist in an automotive vehicle. Now for me because anything 2008 and newer we automatically know that's a CAN bus protocol so I'm just going to go to 15765-4 CAN or controller area network. If you don't know what the protocols are I strongly recommend that you guys read up on what the protocols are and with time you're going to start to know which vehicle uses what specific protocol. If you guys want to know more information about that make sure you guys check out my link in the bio where you get a three-day free trial to my online engine performance and electrical class. Make sure you guys check that out. Alright so what we're going to do here is first things first let's go ahead and go to DTCs and let's see what's going on with this particular wonderful beautiful vehicle we got here with us today. So the stabling communication alright so a couple things we know right off the bat if you guys have seen my other videos on this particular car we do have a PO420 CAD efficiency code we're going to ignore that today because obviously we already know that that code is there. The one that we're going to really focus on today is going to be the P0118 so that's an ECT temperature circuit high right so for me as an automotive technician the first thing that comes to my mind is cool I got a vehicle here that has a circuit high code so when a vehicle has a circuit high code a couple things that come to mind number one either I got an open circuit on the signal number two I'm missing a ground for that particular sensor number three I got a bad sensor right those are some of the things that automatically come to mind if you guys notice because we already had a code here which was for the cat the freeze frame is not giving us any information now you might be wondering why we don't have freeze frame information if we have a ECT code engine coolant temp code the reason why we don't is the PCM is programmed to prioritize emission failures so because of that because we have a catalytic converter code if it was a misfire or a fuel uh fuel imbalance code then obviously yes we would have had that code supersede the because we have a po420 the freeze frame data is still only going to be for that specific code all right so from there we're going to go ahead and escape that obviously we we know now that that's what we got going on so let's go into our live data real quick and let's see if we can spot anything now being that as of right now the DTC I'm having is for ECT circuit high I'd want to um along with my fuel status right my and then let's go to ECT right and then also I want to take a look at the fuel trim so we can see what's going on there and we will graph those a little quick right so the important one is going to be our blue which is our ECT it's showing a negative 40 degrees Fahrenheit so negative 40 degrees Fahrenheit this thing is showing that it's excessively cold okay so what is an engine computer going to do when it detects a super cold condition well when an engine computer detects a cold condition what ends up happening is when the temperature is excessively cold the fuel that is injected out of the injector in a mist form is going to reliquify right so we don't want that because liquid fuel doesn't ignite what the engine computer does when it detects cold sorry cold temperatures it is going to add more fuel and the reason why is because since it thinks the engine is colder and the atmosphere is colder that fuel is going to um liquefy again so it's going to add extra fuel in case of some of that fuel becoming liquid once again or recondensing so that's why the vehicle tends to run a lot richer anytime that you have that kind of fault okay so again here we know that we got negative 40 degrees Fahrenheit so at this point it is going to be something that we are going to go look at at the actual ECT so let's go ahead and head out to the car so let's take a look underneath the hood and let's see what we spot there so what we're going to do right now is we're going to take this paper clip and we're going to insert it into the ECT harness connector and this is why I'm going to do this this is going to help me verify if the circuit the 5 volt reference and the signal return back to the PCM are 100 okay when I bridge it we should have a change on the ECT temperature on our scan tool so we're going to go ahead and bridge it and then afterwards we're going to come back and take a look at the scan tool and see what the data is telling us let's go take a look I'm going to go ahead and insert my paper clip all right let's go ahead and take a look at the scan tool data wonderful so now let's go ahead and go back into our scan data and let's see what our live data is showing us so we're going into live data and we're going to go ahead and go back to our engine coolant temp and we want to set that to a value that we understand which would be Fahrenheit and if you guys notice right now it's showing 284 degrees Fahrenheit so this is letting me know that the circuit for the actual ECT is perfectly fine and at this point if this was a car that came into the shop with this specific code right and the connector itself was actually plugged in because you guys saw that I had unplugged it then I would know that this is a bad sensor now because the sensor was unplugged right the high circuit was an automatic instantaneous clue to me that more than likely this sensor was going to be disconnected or open on the ground side or the signal the five volt reference to the actual sensor let me re-explain it another way just in case it was kind of like what so when we're looking at an ECT an engine coolant temp sensor it's going to be a two-wire sensor five volts five volts go to the sensor based off of the resistance value of the thermistor there's going to be a voltage drop that voltage drop is detected by an internal voltmeter inside of the PCM and that's how the PCM knows what the temperature is of the particular vehicle now in most cases when a car comes into the shop and it has an ECT circuit high your first indication is more than likely that sensor is going to be unplugged or it's missing a ground so then go visually check it right you guys notice when we went out to the engine bay it was already unplugged so if that was a situation the car came into the shop plug it back in and then come analyze your data what I did here was just a verification test by using the paper clip I bridged my five volt reference back to my signal return the PCM saw a 284 degree change which to me indicates the circuit's actually pretty good in most cases in some cases I'm sorry you'll probably see upwards of 300 300 degrees fahrenheit so that would mean that it's shorted right so in this case we know that the circuit's fine and so if you're at the shop and this car comes in it's plugged in unplug it and put a paper clip or a jumper wire by doing so if you see that the the temperature goes back up then that's telling you the circuit's fine now you just really confirm it's a bad sensor now that we learned about ECTs and the circuit and how to run some quick checks let's go ahead and clear the light just so this way we make sure that we reset the vehicle before we send it out back on the road right so from here we're going to go into uh let's see here vehicle status live data I think DTC is here so we're going to go back to DTC this is the first time I use this tool so it's not nothing too crazy very similar to what I'm used to on my Autel Ultra then we're going to hit erase codes freeze frame will be deleted yes that's fine all right cool so if you any vehicle 2010 and newer is going to have PDTCs permanent diagnostic trouble codes so after you clear the light the vehicle is going to store a permanent diagnostic trouble code you could clear you could remove disconnect the battery you could do anything you want but it's not going to get rid of that code what's going to end up happening is once the vehicle goes through its normal drive cycles then it's actually going to clear it on its own once it tests and knows that the problem has actually been repaired so again this is going to give get rid of the parts changers um or the parts hangers that don't actually test stuff just replace parts right so now that we've cleared the codes let's go ahead and escape and we'll go back to verify that codes are gone just one more time codes are gone just our permanent codes so we know that we are 100 percent go and that's how simple it is guys most of the time what ends up happening is we like to over complicate things and a lot of times too unfortunately due to the that's when we struggle with these types of diagnostics when a car comes in and it has a high circuit code first thing you should think is it's probably unplugged or the ground is open right if you get a code that says low circuit more than likely it's grounded and it's pulling it down to zero volts okay so always make sure that you analyze what the code is telling you go look up how that how that component works and then from there you can take it and get it diagnosed and as if i said guys if you like the autofix d1 light make sure you guys check out the link in my bio which also has a discount code so you guys can pick one up for yourself dude it's only 120 bucks for the annual renewal you can't go wrong it's an android platform with all tell software behind it it's a great solid tool also if you guys want to learn more about electrical or drivability make sure you guys check out my link below where you can get access to my online community for only 20 bucks a month and you get access to a lot of my new life classes which are going on every thursday and friday you also get access to our lunchtime class which is usually every wednesday every other wednesday for one hour and you get a three-day free trial you can't go wrong it's cheaper than going out to starbucks so if you guys like this information make sure you guys give us a like and a follow and turn on that notification bell so this way you're aware every time we drop a new video and if you guys have any suggestions for any other videos drop it in the comments and as always guys we're here to better the automotive industry one technician at a time this starts with you and i'll see you guys on the next one