Check Engine Light Troubleshooting: Honda Element DTC P0498 P0135

Check Engine Light Troubleshooting: Honda Element DTC P0498 P0135 – OBD2 Scanner – Relay Testing


Troubleshooting a check engine light on a 2007 Honda Element. The diagnostic trouble codes (DTCs) are pulled with a Bluetooth OBD2 scanner and app, and then an in-depth diagnostic process to track down the root cause is demonstrated. P0498 and P0135 codes appeared at the same time and are shown to ultimately be false alarms caused by a relay failure as determined by relay testing.



OBD2 Bluetooth scanner dongle
OBD2 scanner (standalone)
Replacement relays

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Welcome to… the Grok Shop! In this video I’m going through an example diagnostic process for a check engine light on a 2007 Honda Element. So of course, when you enter your car and you turn your key, all the lights should come on as sort of a test process to make sure all the lights are working okay, and then you should see your check engine light go off. If you don’t see it go off, at that point it’ll probably stay on all the time indicating you have a problem. In fact, this light is your car’s computer’s way of communicating with you that it has seen a problem and it has a DTC or Diagnostic Trouble Code it wants to tell you about. The best way to figure out what’s going on is with an OBD2 scanner device. The one I’m using is very inexpensive but it uses Bluetooth to talk to an app on your phone. There’s definitely fancier ones than this but you don’t necessarily need anything super fancy. If you don’t have one already I’ll put a link to some ideas for you below. Generally all cars sold in the US since about 1995 will have these but make sure you have an OBD2 port before you buy the tool. The location of the port will vary from car to car; here you can see for this car it’s underneath the driver side dashboard. The type of scanner I’m using will pull power from the OBD2 port itself and these ports do have battery power. However, to talk to the computer you need to have the ignition key turned to “On” or position “II” for a Honda. The app I’m using with my device is called Torque Light. It’s pretty good; it’s pretty popular. But there’s a bunch of them out there. I’m not really endorsing this app. Just find one you like and go with it. Of course you need to Bluetooth pair the scanner with your phone. Depending on your tool or app, make sure you see a message indicating you’re properly connected. And so now at this point you can go ahead and select “Fault Codes” and select “Show Logged Faults” because the faults get logged into memory. And now, you should be able to see the DTC’s or fault codes. So, in this case I have a P0498 and a P0135. So the first thing we want to do is make a note of those logged fault codes and then we’re going to clear the codes just to see if they’ll come back. OK, so here we can see only one of the two codes has come back so far: the P0498 A lot of times, codes won’t come back right away because they have to be triggered by a certain series of conditions. So now what you want to do is look up the trouble codes that you got. This particular app will link you to which will give you generic definitions for trouble codes. If you happen to have the service manual for your car, that’s also a great place to look these codes up. And here we can see a P0498 is an “EVAP canister vent shut valve circuit low voltage” and then a P0135 is “an air fuel ratio sensor heater circuit malfunction.” The air fuel sensor is sometimes known as the O2 sensor. One of the first things I like to do when I get a check engine light is to check all the fuses, especially any related fuses if you know which fuses might be related. If you don’t know, just start checking them all. In this case, for air flow issues, there’s a fuse called the “LAF heater” or, “lean airflow” heater fuse. It’s a 20 amp fuse under the driver side – be sure to check your owner’s manual or service manual (if you have it) for more detailed information about what fuse is what. If you do find a blown fuse it’s a good idea to think of it as a symptom of another problem, because when you replace a blown fuse – it may temporarily solve the problem – but most likely, the root cause will remain. For this car, there is a fuse puller in the engine bay fuse box, but I usually just like to grab some needlenose; it just seems to work better for me. So as you can see, in this case the LAF fuse was actually OK; no problem there. But in the process of checking all my fuses, I did find the rear 12-volt accessory socket fuse was blown. You could see the red 10A fuse is blown and kind of compare a blown versus not blown there. Common causes of blown fuses would be like a short in the wiring or a part that’s gone defective and maybe even shorted internally; and conversely, not finding a short may mean that you don’t have those problems. If you’re able to get your hands on the service manual, I would recommend it because it can help troubleshoot the problem. Here you can see in this case, the first thing they recommend is to clear the code, which we’ve done already. Since the code reappeared, we need to do some testing at the EVAP canister under the car. Since we’ve got to get under the car, we want to make sure the car is fully supported on jack stands and has a backup support as well. If you’re curious about the procedure I follow for this just check out some of my other videos for that. Most of the evap stuff is situated just aft the gas tank which is kind of just inside the left rear wheel. There you can see the canister – the big charcoal canister – it’s one major component of the EVAP. So now, looking at it from the other side, the EVAP canister shut valve is just to the right of the canister, and here you can see the 2P electrical connector. So, one basic test they don’t really tell you to do in the service manual is to test what’s going on with the signals on these wires when you turn the ignition to the ‘On’ position. So I’m just going to do that now by connecting the voltmeter ground to the frame. So this test is pretty simple: you should expect battery voltage on one line and the other line to remain at ground. I find a paper clip to be really helpful. I just stick the paper clip in and then clip my voltmeter on to that And here you can see I got 11.9 volts, a slight drop from battery voltage, but it seems to be OK. OK next we want to test the shut valve itself and this can be done with the part on the car, but I took mine off because I wanted to go ahead and do some clean up on my EVAP system. But to test it, we want to test the resistance at the connector and it should be 25 to 30 ohms. So pretty much the shut valve is just a solenoid. What that means is we should be able to apply battery voltage and see the solenoid in action. What you don’t want to do is hook it directly to your car battery because you could fry the part that way. Use something like a 9-volt which is current limited just to get enough voltage and see the action. And here we can see the shut valve’s operating fine. So having done all the tests, everything checking out fine, since I was under the car I figured I’d go ahead and clean up the EVAP system just because I’d read about the spiders getting into the hoses and clogging it up and I wanted to make sure I didn’t have anything like that going on. Getting the system pulled apart where you can get to everything is kind of a daunting task. I don’t necessarily recommend it unless you really feel like you might have a chance of having these spiders or some other problem. But this is the part where they seem to come in at it’s called the drain and it’s way up in there. At the end of all this work I didn’t find any spiders. It was really dusty so maybe it was good that I cleaned it out, but probably a lot of work for not a lot of gain. So moving on with a diagnostic procedure, Step 9 here. Whenever you see this “jump the SCS line with the HDS”, there’s a way to do this (that’s the service control short); there’s a way to do this manually – you don’t need the HDS or the Honda diagnostic tool. So here you can see a pin out for the OBD2 and line 9 is the SCS so basically we need to tie line 9 to ground. But so what they want us to do is jump that SCS line and then test pin 19 of the “E” connector of the ECM. So here you can see line 9; if you look carefully the pins are actually numbered on the four corners there. So if you wanted to get fancy you could actually make your own OBD2 connector to short this out. But I usually like to keep it simple, so it’s back to the paperclip method for me. So where is this connector E right? Well it’s back to the service manual or maybe a Google search to turn up the locations of these connectors at the ECM. Pretty much they’re behind the glovebox, so you need to drop the glovebox. If you don’t know how to do that, check out my video on fixing the AUX port for the Honda Element. These connectors come off pretty easy. If you look, there’s a little tab; you just put your thumb on the tab, make a little squeeze and ease it on out. You don’t want to damage any of the wires or connector,s obviously. Next, we need to ground the voltmeter. I just set my ground to the same ground that we did a minute ago for the SCS line. So now, using the paperclip method again, we can connect a paperclip to the E19 port on the wiring harness, and test the resistance between that port and ground and it should be infinite, indicating no short and it is so this eliminates the possibility of a short along the wires leading up to the connector. So now, with all those possible causes of the DTC being eliminated, the service manual sort of runs out of ideas and says “hey, try replacing your ECM!”. But, before taking such drastic and expensive measures, I decided to ponder some wiring diagrams. So recalling that I also had a P0135 code at the same time as the 0498, and if you think about it – it would be pretty unusual for two unrelated components to fail at the same time. So I began to think maybe this is a clue, right? So I decided to start browsing some of the wiring diagrams in the service manual. On a single diagram, I was able to locate the critical components of each of the two circuits affected by those two DTC’s. So the two critical components – the AF sensor and the EVAP canister shut valve – are there in the red boxes and you can see that they’re actually connected by this white wire to a AF sensor relay which is behind the glovebox per this diagram. Then, I was able to find another diagram in the service manual which showed me the actual location of that particular relay. Once you get in there you’ll see this cluster of four black relays they’re all actually the same specification relay, but the one in the back right is the one that we need to get to. And it’s really hard to get these out by hand; I like to use some needle-nose and give a little jiggle. But you need to sort of remove the ones in front to get to the ones in the back. And so it’s just something requires a little patience and you don’t want to be too hard on these things or the harness; you don’t want to break the harness below which is kind of a flimsy little plastic harness. Also, just to be on the safe side, make sure your ignition’s off so you don’t inadvertently short something. If one goes flying on you behind there, you can actually use one of those strong magnets and put it on the end of a screwdriver and reach in there and suck it out. Since I had to pull at least 3 relays out, I decided to go ahead and just pull them all on out so I can do the test and figure out “ok, I think I may have one bad relay but maybe there’s others that are failing too so I’ll just test them all out.” So for those who may not know, a relay is basically a high current switch which is controlled by a low current signal. Since these are 12-volt relays, a 12-volt signal will close the switch. So basically you can apply 12 volts or somewhere in that neighborhood to the low current terminals and you should see the high current side switch close. Now on these particular relays, the fat copper colored terminals are your high current terminals and the thinner brass colored terminals are your signal terminals. So what I’m going to do is I’m going to apply my ohm meter across the high current terminals, and then I’m going to take a 9-volt battery which isn’t even really charged all the way up (but… nine volts is fine.) and I’m just going to touch it to the low current side. What we should expect to see is infinite resistance until I apply the voltage and then we should see the resistance drop to zero indicating the switch is closed. And yeah, right there – if you listen carefully – you would have heard a little fluttering sound. It should make one single click, indicating the relay’s closed and then we should see the resistance drop to zero. That relay sounded a little funny and the resistance did not drop to zero, so it’s probably the bad one. So now I’ll just go through and test the rest of these out. This relay is giving that definitive single click sound, and going straight to 0, so it’s probably a good one. OK, so just to be sure, I’m going to re-test that flaky relay one more time. So yeah, while the one relay is not in a complete failure mode, it’s definitely intermittently failing and it needs to go. Luckily the other three relays checked out. So for now it can just mark the bad one and swap it with the one next to it – which is the rear 12-volt accessory socket – and see if this fixes the problem. So now with the two relays swapped out, I go back to my OBD2 tool and see if – when i clear the codes – do they come back or not. I sped up this process just a bit so it’s not so boring but as you can see the codes do not come back. So long story short, if you see these two DTC’s you might want to check this relay out. OK so now what about this part? My car is about 12 years old and I’ve never had to replace any of these, but here’s the part number and it’s made by Omron, I think it’s how you pronounce it. According to the Honda eStore, you can get them for 25 bucks from the dealer straight purchase or $21.27 through an e store purchase. I found numerous vendors on Amazon selling these as well. You can get them in sets of two, four, or five and it’s much less expensive than the “stealership”. Of course, I’ll link these below if anyone’s interested; the reviews are good but you know how reviews are. I haven’t tried these myself so if anybody has any experience with these or others let me know. So that’s it for this video. I hope you found it helpful. If you did, be sure to thumbs me up, share me, or throw me a comment. Be sure to subscribe if you want to be in my future video release loop. But as far as general DTC troubleshooting goes, and in particular P0498 and P0135 simultaneously on a Honda Element, that’s how it’s done. Thanks for watching.

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