Causes When Oxygen Sensor Replaced and Code Keeps Coming Back

Fixes when a changed O2 sensor code keeps coming back.

How to Test Catalytic Converter Video:

P0171 Error Code Video:

Be sure to check for other codes.

Posible Causes:
⦁ Oxygen Sensor Circuit
The Error Code Didn’t Clear
O2 Sensor Wiring Open or Short
Blown Fuse

⦁ Exhaust is Clogged or Leaking
Catalytic Converter Clogged
Exhaust Leak

⦁ Engine is Running Rich or Lean
Bad MAF Sensor
Bad Injector
Vacuum Leak
ECM/PCM Failure

By using this information user assumes all risk of use.

[HappySox_TheOriginal]

I replaced all my sensors and kept getting the same code. I tried everything. Then I watched your video. You stated exactly what the sensors designation was and I went to look. BAM…. 850.00 later and I could have just replaced the missing 15A fuse. You’re the man!!! Thank you before I would have taken it in somewhere and spent MORE money on it.

[HiddenValleyHomestead]

Yeah but if its a clogged CAT then you'll get a downstream O2 sensor code as well! But the upstream sensor will definitely be a number of issues like you said

[monkey]

I replaced both o2sensors and the light didn't go away, my problem was that connection was not plug in all the way, so I plug it and the light when off.

[Flexx]

Why is this video under watched and why wasnt this my first video suggestion for this code ..!?!? This is an excellect video of everything abt this code that i bave been through since having it lol

[carlosk]

Nice video it's comprehensive yet short and to the point...

[debbymorden]

2013 Chevy Equinox...changed O2 sensor upstream & downstream.. 4K road trip was fine entire time...light back on..replaced both srnsors again yesterday...light back on today...its running great...

[nifrios]

You ROCK! thank you so much for your clear and concise analysis of returning O2 sensor codes, very helpful🤘🏼

[lisaalony]

For us, after replacing two O2 sensors and still the same problem, thanks to this video -- it was a cheap FUSE!

[crissiehinkle]

Thank you!! You've given me a place to start looking! I replaced all the O2 sensors and got the code P0154/0155 after that. Plus P0302 and MAF sensor code P0101.

[shauncunningham]

Thanks what a great video know your stuff and I appreciate it. Just want to say thank you. You have a great day

[robwhiff]

I have an iS 250 Lexus 2006 What about spark plug and coils could it cause p0138 ? I put a brand new map sensor and a brand new O2 sensor. and I also noticed a leak on the flange coming from the manifold to the converter. Fix it and still getting code…thanks

[emcycles]

I have a 2000 Chevy Silverado 5.3 just replaced all four O2 sensors, gas cap fuel filter and another little chip plug-and-play deal on top of the fuel tank. I've reset the OBD2 service engine soon after each service and continues to come back. Along with my brake light and ABS light. It might be coincidental but all happened same time. Any ideas?

[.Licks]

I have Both o2 sensor codes and a P0302 Cylinder 2 code I swapped coils and spark plugs… my final guess is a clogged fuel injector/ and or fuel pump and filter. 2014 ford mustang GT (5.0)

[MarkConwayTheBurgerKing]

I have replaced upstream oxygen sensor on my 2006 Hyundai Elantra.
Plus, injectors, VVT solenoid valve, map/MAF sensor, Purge Valve Solenoid, PCV valve.
The P0133 still coming back.
Normally at high speed.
Only clue I have after smoke testing last week.
Throttle body butterfly spindle shaft leakage Both ends.
Will this throw off the Oxygen sensor on high speed deceleration?

[shauncunningham]

Also I had a question for you. They said an autozone I had it found out what my codes were and I got APO 430, and I changed it. The 02 sensor bank 2 AM I supposed to change both of them on the right side. I changed the upper one I think I'm just gonna change the lower 1 also, just for s**** and get. Wasn't too sure thanks have a great day

[toddhubbard]

Please explain if you would how an exhaust link underneath your truck or car can affect how the 02 sensors read the ambient air (outside air)(which now has exhaust fumes in it from a leaky exhaust pipe) would alter the downstream sensors ability to send the proper information To the computer Which has to make adjustments according to reading the downstream sensor is getting.
Remember there's an exhaust leak under there. So the downstream sensor maybe the upstream sensor as well is confused.

[yashicasmith]

So i have a 2008 Honda odyssey and been getting the codes po155, po134, p2240, p2251. The oxygen sensors have been changed numerous times along with the catalytic converter, the codes keep coming back it's really been a pain in my side for the past 5 years I've spent so much money trying to get these codes cleared. What can you suggest?

[CrazyAylaa]

I’m working on this 2013 ford Taurus with the 3.5 eco boost flex fuel has codes for po145 and bank one and bank two down stream sensors stuck rich and I’ve done a test on the purge valve and vent valve coal canister all working fine and checked the map sensor fine checked the o2 sensors connection fine and did a leak test on the system fine and the o2 sensors are in the 5v range idk much els to check I was gonna pull the o2 and look at them as well I’m wondering if it’s the VVT solenoids there leaking oil I was gonna check and see if there good or not and the seals oil is fresh any ideas would help thank you for ur time

[worldpeace]

I got the cat changed last year for catalytic converter P0420 error on my 2016 CRV. 6 months down the line I got the P0139 error. I changed the downstream sensor this time. 2000 miles more I again got the same P0139 error. I called Denso and they sent me a new sensor because of warranty. I called the mechanic to reinstall the downstream sensor and he says P0139 error may be because of upstream sensor also and recommending to replace upstream sensor. I am so confused this is driving me

[jonathancritzer]

So I've replaced the mass air flow box and o2 sensor and fixed the exhaust. It's a 2003 ford focus . Still doing the same code and running and idling weird but hasn't put a check engine light again?