O2 Sensor-No Activity Case Study: '04 Mitsubishi -Part1 

I like how Ivan has grown with his diagnostic skills after all these years and no longer looks like a young manchild, and Eric still looks the same.

6yrs on, well 7 actually. These videos with Eric and yourself are priceless. You do know Eric's looking for new ideas. Maybe it's time for you and your family to have a cheeky wee holiday in South Main🙂

wow this is like the 1st Superbowl recording being found!!!! thanks Ivan & Eric.

Great video Ivan you and Eric are truly the RU-vid dynamic duo I'm a mechanic myself and I watch your videos and find them more interesting than cable TV my son looks at me crazy and goes dad you're watching those guys again lol everyday thanks for the great videos and you an Eric O keep up the great work together

Interesting! I'd like to check B1S1 harness side signal wire and ground independently to a known good ground to see where that minus voltage is coming from. Looking forward to part 2 guys.

Ooo so you guys knew each other! The best mechanics on youtube!

You guys are such nerds about Diagnosis....And I Love It! And so enjoy watching..Thank you! Don't stop making Vids

Great to see this couple working together. Two masters of the autodiagnostic field.... Congratulations

Ahhh the old Mitsubishi! What a fun project that was. We need another in depth floor mopper to work on! Wish you were up here for this Duramax I got in the shop now. Hoping it turns out to be a good learning lesson too!

You guys make some excellent case study vids. Looking forward to seeing what was up with this one. Man this thing sure had it's share of tampering.

Can't wait for Part II. You guys are Great to watch!

Don't leave me hanging!!!!! I feel like that was a season finale and now I have to wait for the season to start back up. Can't wait for part 2

My vote is a shorted heater wire to the b1s1 signal wire. If I'm reading the correct diagram, the oxygen sensors share a sensor ground with the mass air flow sensor. If sensor ground had been lost, would there not be codes for the MAS? Awesome video guys, can't wait for part 2!

I loved the technician comments, other shop cannot fix after consulting Haynes and factory flow charts . Maybe try plugs wires and seafoam

Thanks to both for all the great trouble shooting tutorials.

This is awesome! You guys are Diag Beasts! On to Part 2!

I just love the way you bounce of each other and brainstorm this. The look on your face when Eric said increased resistance, and your eyes nearly popped out, pause then correct. I know Eric just got it mixed up but your reaction was priceless. I'm along for the ride all these years later as I watch back vlogs.

The way you 2 work together is amazing. Love to watch you guys together. Great video.

Two beasts together lol.... Masters mechanic in action. Greetings.

Great video, I agree with Toyota Tech , retest S1B1 with A known good ground on the scope. Meter reads difference in potential so the o2 ground would be my next test. Look forward to next part :) Cheers.

Ivan is a sharp young man. I've been watching him, and when he gets calls from allover the country he is good. To me he goes backwards sometimes but finely gets there. Would like to work with him about a week. I feel sorry for the guy that owns the car, to be treated like he was treated is BAD. Garages that do stuff like that need to be closed. Me I would cut him a big break on labor on this car. I know can't do this for everyone but once in a while it can be done. It will come back to you in the end double money. Seen it happen too many times. Keep up the good work Eric and Ivan.

Eric and Ivan, the dynamic duo, sweet, give us more!!!!!!!!!!!!!!!!!!!!!!!!!!

Hey Ivan; as usual a great watch, you two guys bounce off each other quite well. You also keep each other honest with the theoretical analysis; which adds to the theatre of the job (write that down). Best of Luck guys!!

Hi guys, my best guess is a short between the loose cable you found on the connector of O2S 1 bank 1 and one of the heatherwires of that sensor in the harnas. Or somewhere in the connector of the PCM. Good luck, looking forward to part 2. Well done so far.

Very intressting.enfach schön euch beiden über die schulter schauen zu dürfen.cool eure ZUSAMMENARBEIT.wünsche euch immer gute gesundheit.danke für das video.lg.

Great video and wasn't the least bit distracted by the next door neighbor's daycare center activity.

The owner of this vehicle just entered the lottery with you two on the case. I'm betting he'll be a winner! As for an idea?... none. I'm a DIY guy just trying to catch up on technology.

This is a quote from the Ford service information OBD2 theory and operation on their 2015 gasoline vehicles that is free on their website. Not sure if Mits was using something similar, but possible. "As the front UEGO sensor ages and gets exposed to contaminants, it can develop a rich or lean bias in its transfer function. The rear bias control (also called FAOSC - Fore/Aft Oxygen Sensor Control) system is designed to compensate for any of these bias shifts (offsets) using the downstream HO2S sensor. The "FAOS" monitor looks for any bias shifts at the stoichiometric point of the front UEGO sensor lambda curve. If the UEGO has developed a bias beyond the point for which it can be compensated for, lean (P2096, P2098) or rich (P2097, P2099) fault codes will be set." Rear fine fuel trimming seems to be a big mystery in my opinion. I really haven't seen too much literature on the subject. I've run into all kinds of forum techs saying they used rear trimming on vehicles going back into the 90's, but haven't seen factory service information to support that. There are rear trim data PIDS on some vehicles that will show on our shop's scan tool, but I've only seen it active on some of the later model Fords. Here is another quote from Ford when FAOSC appeared in 2004. Wonder if your Mits is a PZEV or has Cali emissions. That would explain the special clean air BS from the owner. Maybe they meant it produced less emissions. "Some 2004 Partial Zero Emission Vehicles (PZEV Focus) will utilize three sets of HO2S sensors. The front sensors (HO2S11/HO2S21) are the primary fuel control sensors. The next sensors downstream in the exhaust are utilized to monitor the light-off catalyst (HO2S12/HO2S22). The last sensors downstream in the exhaust(HO2S13/Ho2S23) are utilized for very long term fuel trim in order to optimize catalyst efficiency (Fore Aft Oxygen Sensor Control). Ford's first PZEV vehicle uses a 4-cylinder engine so only the Bank 1 DTCs are utilized." Sorry for the long winded post.

One of the best technician on RU-vid ever

OK I'm a rookie, that's why I'm watching but as soon as I saw 5 volts I would have went to the ECM and would have been expecting to find the reference signal coming out on the wrong pin either because of an internal problem with the ECM or because someone before me swapped some wires. It was hard for me to watch you keep proving the sensors were working when I wanted to go test the ECM. Can't wait to see what you find.

I believe scan data of O2 voltage will not show negative readings, they will display as positive on the scanner. If so, you could have a voltage feed on the signal ground of the O2 sensor on bank 1. Did you take voltage readings koeo at the harness side with the O2 disconnected? thanks for your time, br.

Wow!!!.... got you both on the same channel!!!...super awesome man!!👍👍👍👍💪😎

My guess is the replacement O2 on B1S1 has the wires transposed in the connector, so the sensor ground is in the heater feed position and the sensor ground is in the signal wire position, therefore feeding 12v into the signal line via sensor, hence the negative voltages seen in multimeter mode. The white/black has been cut because this totally blew someone's mind!

Two Master mechanics , great video 👍

Interesting one!!!!...i've been intrigued of what is going on with that mitsu!!!!....but you can turn it on and off, on and off, and everything runs fine!!!!...wowww!!!!!...what about a test drive???...does it stall??...because revving in neutral is one thing, but when is under load something else can appear!!!!.... interesting!!!

perhaps the wires on the o2 plug have been mixed up some how, seeing - neg volts on the wire to your scope maybe this is the ecu pulse width signal from the ecu for the heater, maybe ,thanks ivan for sharing cheers

Caution Caution Caution! At 12:53 Eric holds up a can of brake cleaner to spray into the intake as an "enrichener" for O2 sensor diagnosis. Eric's can has non-clorinated cleaner. Another common type of brake cleaner (from CRC) has tetracloroethylene. That compound can produce phosgene, a deadly gas, when heated or combusted. Phosgene will kill at very low concentrations (4 ppm) when inhaled. Please don't use brake cleaner in this test unless you know it is not clorinated and you are sure that it won't break down in a running engine into deadly gases.

You have a black hole creating a tear in the space time fabric which is giving you a negative voltage.

Would it have made any sense to just swap the bank 1 & 2 O2 sensors to see if the error code followed the sensor or the bank?

You mentioned that the previous garage substituted a known good PCM. Time to look at diagrams for sure.

Ivan my buddy. Good work fellas

two auto repair RU-vid giants in the same video. How great can life get?

Dang, where you guys been hiding this rare gold??? When are you gonna post the HD Bigfoot interview, and the 3D J.F.K. assassination videos???

You can tell Eric was super annoyed with the customer.

I do like it when you and Eric do one of these weird diagnostics together. That really is a strange problem.

Were the o2 sensors plugged into the proper connectors? You said they were keyed roght? I would be verifying integrity of the wiring harness and make sure the wires are in the proper places. Also did you scope the maf sensor on a snap to see what it looks like? I wonder if you have a exhaust restriction that is skewing your numbers. Did you check Exhaust backpressure?

It acts like a computer ground but more like a short to voltage especially with the -10VDC reverse polarity actual data vs processed data or short to voltage and the PCM sensor ground can't handle the currecnt so it is reverse current searching for a ground. That kinda explains the 5V reading and the original -6.7 VDC and don't know if the computer then is going into a protection mode and that was driving the -10,67V which I think was then showing 1.275V vs. the initial 5V reading...I like the ones that make you think. I'm using the data the customer provided stating the PCM was changed and that didn't fix it but I never trust that data. I never guess and let the DVOM & lab scope provide the data but I'll play along. Need to read the sensor grd wire disconnected and if reading voltage disconnect PCM...this would get me excited to troubleshoot b/c it's different.

If these two guys can't fix it, it can't be fixed.

It's obviously the clean air sensor plugging the O2 sensors lean. Less fuel=cleaner air. Easy Peasy. Case closed. Bob's your uncle. Time for the Super Bowl!

Heyyyyyyy is nice to see you together .makes me happy 👍👍👍👍👍

That's a good video.. thank you !

Mid 80's Ford was famous for the .5 year models. Had an early 89, went to replace sending unit...only 89½'s were available had to buy a new gastank as well.

Great video guys. Can't wait for part 2. My guesses are shorts in the harness, bad ground reference, some combination of those, with bad PCM a distant third.

From my experience the OBD-II HEGO Heater Monitor code is a two trip (two drive cycle) code. You can have an open heater circuit, and I mean open, not intermittent in any way, and the PCM will not set a code (illuminate MIL) until the 2nd trip (drive cycle) has completed. The variability in this monitor is if the module will set a pending code without the MIL. Which would make sense. Why else would you have a pending code software mechanism if not to store the first failure per completion of a valid drive cycle. To me it would be a natural step in a software state machine. But, I have seen results where no pending code is stored. So I find it a little confusing when comparing OBD-II implementation from one OEM to another. Obviously, there is some standardization in the OBD-II monitors, but I find the details of how each OEM implements the monitor steps can vary, especially in pending codes and freeze frame data. You have to do a fair amount of testing to actually back out how one OEM (which may vary between divisions and/or models) has implemented the monitors.

I love what u guys do!

No idea how this "oldie" showed up for my consideration. I like it, you gents are great as a team. Do we call you the Dynamic Duo? The only thing lacking was CC being turned on. Thank you for the video.

I can see a common B+ coming from the MFI relay, then going to the Mivec valve, injectors, CKP, EGR valve, EVAP, then all the oxygen sensor heaters. Nothing related to the signal wires.. Obviously the sensor isn't producing the 5 volts, it's gotta be coming from somewhere. My guess is that it's human caused. Someone put a jumper somewhere or switched wires somewhere creating backfed voltage. Similar to the crank sensor circuit of that Acura TL possibly!

yes, the video looks like its from the archive. you both are so young.

You should do more of this type of videos

Haven't seen part 2 or 3 yet. But it's obvious this car needs the clean air sensor replaced from the muffler. And while you there might as well seafoam the fuel system and rotate the tires

Somewhere in video MAF sensor shows around 5-6 grams per second... Is it too much for that engine?

nice one ivan, o2 showing -5~10v ? how is the scan tool showing neg. o2 voltage? my guess is where going to see some crustys.

I think the only place you could measure a negative d c voltage is at the alternator with bad diodes. Check with a scope the d.c. voltage wave form output from the alternator.

Hi Fellas, Thank you for all the wonderful tech video, I own a Body and Fender shop that does its share of mechanical work as we. You have been a huge help on the many passions I have been stumped . I did want to ask a please hellllp ?. I own a BMW 750 that is having a similar issue Bank 2 sensor 1 no activity or on occasion next to no activity. Bank 1 sensor 1 was out at one point however seems to be online again. both upstream sensors are new. could the down stream sensors contribute to this issues . I've nearly pulled the rest of my hair out

You two sure look young!!

5v on a sensor signal?! bad grounding perhaps

I wonder what could be the cause in a situation were there are no codes or check engine light, but the downstream oxygen sensor remains inactive? I have this problem with a 2.2 DGI GM engine. Ever since I bought the car, the second sensor is constantly inactive. I replaced the sensor twice with what the tech specs says for the car. And it remains the same, it results in very poor fuel economy.

So is the black resdueon the connectors a bad thing?I don’t have a reader and the mechanic shops around me won’t work on it because it’s not an American Vehicle

FYI Eric is a great tech and we all learn along the way. I started doing computer control in 1982 OBD1 and thought it was a joke and I was wrong now at 60yo its about CAN and problems that you MUST put your head around to make a diagnosis. This video shows that No reason short term would be -25 after running that long and post cat is not conern?

Exelent team guys ....

I'm going to guess a grounding issue. They seem to cause odd issues and with the corrosion you guys see over there that's my guess.

My God Ivan how old were you when this was done 16? Great to watch

I remember this case, In the end it turns out to be the wrong wiring harness for this motor.

I need a great diagnostician. I have a 2002 Isuzu Axiom with a P0160. B2S2 inactivity. Wires good. All signals present for he O2 sensor wires. Installed 4 new sensors same problem. Changed again B2S2 sensor again after playing roulette with the 4 sensors. Changed plug after I convinced myself that maybe the problem. It is not. Cleaned MAF sensor. New spark plugs. Great air coming through the catalytic converter in very strong pulses. Played roulette with the coils, just in case. It is a mystery. I am now thinking a pcm/ECM might be needed. Any wise words for the weary?

Way too much crap on newer cars. Just asking for trouble. What was wrong with the old reostat for the fan speeds and hot water through the heater core. Kept me warm for 40 yrs

Ha , I'll be real short, I have no idea what happened after you said bank 1 and bank 2 . LOL

Ok my o2 sensor were cut off my 04 mitsubishi galant I just need to know what o2 sensors go where

Wearing a rings and watches working on an engine...😳

Could it be also bad replacement parts?

Nice background music. Screaming angels? Lol. Need earplugs 😅

Please no more ads

Two of my favorites, just add Mat from Schrodinger's box and Scanner danner and we will get grand Four ! :D Legends !

can we replace the old single wire o2 with new triple wire o2 ???

Hey Ivan, glad you posted this video.

1987 chevy v6. I had issue with o2 sensor. the car ran but it ran like misfiring. I use the scan tool notice the o2 sensor was not responding. It grounding the cpu low and behold the sensor was really rusted in. 45 minutes later the car ran like a champ.

other wire would take power away?

Gotta watch parts 2 and 3, but I gotta say a bad ground or a bad PCM.

Oh, time travel… Looks like you guys have aged well

Now they should do Eric O, Ivan and Rainman Ray's

Hey Eric, Ivan where's the Russian Techno music with the great beat.

First time seein 2 sets of sensors on a 4 cylinder.Have'nt a clue what's causin it.Sensor operation is A1. Would suspect wiring to sensors or pcm problem,only a guess.

The galant’s are very reliable just do regular maintenance 👨‍🔧 but in this case it actually needs repairing

B1S1 at 5V does that mean it's a wideband sensor?

This is like when Sammy Hagar joined VanHalen! Super group!

When two worlds come together

I'd be calling in Scanner Danner to fix it is my guess.

Love a cross over. L.o.L

the fix is a little sniff of brake clean. the 02's would wake up and get high. kids stay away from sniffing this

It would be very nice If Ivan would not change the screen as the camera zooms in when Eric is trying to show us something. and not be on the front of the camera blocking the screen view. and not repeat everything Eric just said again. Sorry but its hard to hear two ppl taking at the same time.

Lol I did a chevy I think it was it had o2 codes and kid you not they where connected to each other the 02 sensors and the car connectors where on a loop