Dude, I am a mechanical engineer, amateur car DIY, literally you are not a mechanic, you are a nerdy engineer with a mechanic job... Love your videos so much...of all the Techies/engineers/mechanics i have met, FEW can diagnose something until they KILL IT WIDE OPEN... like you do, electronics level, engine parameters, timings

Dude! YOU ROCK! Love the video and will check others you have. Thanks for all you do . It;s great to see a step by step, logical approach to diagnosis and repair. Keep on rockin'

I love working on cars. I wish I knew 1/2 as much as you do.

hi matt that's the problem I'm having on our focus secondary air and check everything and now you just did clarified to me and change a bad solenied .I'm not one that go to a parts store to get what the scanner is telling me. you're good in details explaining what's up.thank you and wish you were closer so(car wise).keep up the good work and God bless.

I'm not even a mechanic and you made this look easy. My '01 Silverado has a random misfire code and after 2 mechanics looked at it both had different opinions, and both were probably wrong. Most likely an intake leak based on what I learned here. Keep up the awesome work!

You are so great Schrodinger! I am ASE certified in brakes and thanks to people like you, Eric the car guy, and Scanner Danner, I might just pass my ASE test in engine performance. I failed it 3 times so far! I may even be able to get a decent paying job if I can somehow become as good mechanic as you guys!

Great video! I am a former Mercedes Benz tech and currently a small auto repair business owner and what you are showing is vital and I subscribed because we can all learn something.

Good clip. I really wanted to watch the vacuum dial but it was flooded out. I enjoyed the part two too (part to to? Than can't be right!) . Always good to see that final histogram act as it should. Son in law's car has got lean codes setting. I can't wait to get the scan tool on it. The shop told him it was most likely a vacuum leak without looking at it. They were planning to replace a lot of hoses. I gave him my scan tool and your links.

Thank you so much for posting all these videos, because of you my diagnosis skills have improved. I am no longer a "parts changer" lol

Out of 137,619 views, you only have 537 likes!?

you're such a smart ass and i love every one of your videos lol

Had a P1415 code only. Replaced the left secondary air check valve. The old one was definitely plugged. Cleared and ran the truck. MIL light back on, checked and it had a P1416 code only. Cleared it to just make sure it wasn't an anomaly and MIL light came back on with a P1416 and P0410 code. Replaced the right secondary air check valve. Will run it today and tomorrow and see if that is all what the problem was. If I get the P0419 back, I will run through your diagnostics and check the rest of the stuff. It's my truck, so I don't have to answer to anyone but myself. Thanks for the diagnostic info.

Can I suggest that you turn the work lights to face the wall or ceiling rather than into the camera lens. The light will reflect off of the white surface and produce a much softer light more suited to filming. Also I am still searching for that youtube channel where a professional mechanic makes videos on molecular biology.

nice diagnosis

Great job well done.

It took me a week I watched videos I was able to download diagrams I mean I didn't end that research on my Milan's secondary air system which happened to be that my year Milan is the only car from Mercury that has this system. I will never buy a car with a California based emission system ever again. I had a p0410, p 0491, a p0300, and p2257. I started by changing the diverter valve, did nothing so I thought maybe it could be the solenoid, plus the 40amp fuse would blow each time I started the car. So I had over a dozen fuses just in case for a week. After I replace those I still had the same lights except for the p0300. I finally caved and did the pump the p0410, and p0491, finally went away when the new pump was replaced. Yay, then I put in the new fuse again start the car and boom wrench light, car wants to stall. it's a very high then immediate drop to low idle and check engine light. Good news is now my new pump works, but will not turn off on its own over about 40secs, even when I turn my car off the pump is still running. At this point I know I may have to do some major wiring testing. And I'm terrified of it because my smog pump relay and PMC relay are one in the same. I also noticed the fuse is not blowing anymore. So two positive so far. Still I turn my car off, run a scan the skin device once I put my car in run but immediately turn on my secondary air, or smog pump. I also noticed that the only time it would go off is if I banged on my junction box. Anyway the scan pulled up 2 opposing codes p2257 and p2258. 😭 I checked all the hoses found the hose that goes into the manifold from the diverter valve solenoid was extremely cracked and dry. that was a difficult hose to replace because you can't find them around here. I did find one at a junk yard in great condition, another diverter valve as well as the solenoid that's attached to a just in case, and out of extreme caution I even took a relay from the exact same year fusion as my Milan because that's the only one that would match to my your car. I replaced those all again, except the relay because the relay treat asked it was good. I did not know that every single time that smog pump started because the diverter was not feeling the vacuum it would which shorted solenoid which is why the pump kept going. After I replaced it all again along with the hose no change. Now though I was smart enough to turn the car off immediately and start my pump immediately to prevent further damage. I would still have to bang the junction box to get the pump to stop though which put a light bulb over my head the relay needed replacing possibly took out my old relay put in the new one started the car 1500 RPMs stayed stayed in a wrench drop down to about 80 still no range put it in drive went around the block very good came back parked turned off the car got out listened the pump wasn't running. Okay so far so good, started my car again that would be the big test held my breath turn the key no wrench and because my engine was already hot the RPMs would go into idle 60 70 RPMs no wrench I've never felt such relief in my life. I got to realize that there was something loose within the relay that was causing everything to short out because every time I hit that junction box it would shake something back into position within that relay causing the pump to turn off. Took the old relay inside my house tested it don't behold was not working properly I don't know if me constantly starting the car with the bed solenoid or the bad diverter or having that fuse blow so many times cause the relay to finally pop but every single check engine light is gone and it's not even secondary for the p0300. I hate the secondary systems and I'm going to make sure I do not have them with any other car they're so frustrating

I had the same problem but the dealer want 870.97 for my problem to find out is was my evaporation holes that was leaking.. I away ask for any part any dealer or shop.. And thank to you i got a chance to school a dealer tech... Who did the same thing... After all was done the tech worked on my car for free because it wasn't the problem.. Evaporation holes boot ends... The one going from motor to sensor. Someone there remove fuse label stud1 witch is power the air pump.. Let just say the service manager want happy when u school the pro on there mistake. So again thank u.. This video help.. I gotWas getting mad that the truck been at the dealer five time and they couldn't find the problem And something simple as leak evaporation holes...

Thanks to your last video where you explained it in excruciating detail, at

Good stuff verifying with propane & smoke... I never got into using the propane method myself. I think because I was always worried of it igniting from the spark in the distributor cap (when I first started every car had distributors) as well as the propane stays in the shop (heavier than air).

Hi matt great video with brilliant audio and video quality! When u were talking about the massive clue at 8min 53sec I thought u were going to point out the low manifold vacuum pressure at just 12in of mercury I thought it should be in the 16 to 21 range anyway just an observation thanks and keep up the good work. Sandy(Scotland)