code PO136
 

Hi

Can anyone tell me what this code is for-both O2 sensors have been replaced as well as the exhaust flex pipe-after the CEL is reset by my mechanic evertime I remove the tight gas cap (turned at least 3 clicks or many more to secure firmly)-after about 2-5 miles the CEL comes on again-any ideas so In can also share this with my mechanic and save money in diagnosis charges?-I have a 2001 Elantra

Circuit low voltage to the O2 sensor after the cat:
OBD-II Trouble Code: P0136 Oxygen O2 Sensor Circuit Low Voltage (Bank1, Sensor2)

If you have replaced the O2 sensor then I'd ckeck the connector and the wiring. Also, check the sensor because you may have gotten a bad one. Was it a Hyundai sensor or an aftermarket part?

PO136 code
 

Hi

It was an aftermarket-this is the second O2 sensor since the first one registered no voltage at all-per the mechanic this new one registered voltage. Hyundai sensor is relatively expensive

Hyundai sensors may be expensive but at least they work. And I'll bet one Hyundai sensor is cheaper than buying 2 aftermarket sensors. You get what you pay for.

O2 sensor
 

so that is the likely problem-I just want to get the car fixed correctly-I can complain of the price all day but if thats the problem then I sure will put one in. Thanks for your reply

I wouldn't replace it without cecking the sensor and the wiring first.

O2 sensor
 

Thanks


I plan on doing that-appreciate your help

Wow, so I came here specifically to check on this exact same issue and whaddyaknow the very first thread is about my very issue.

This is my mom's car - 2000 Elantra ~185k miles. The past 20-30k miles or so have been issue after issue with this car. We're trying to get her another year or two out of this car.

Anyway, like the OP, I replaced both 02 sensors because she was getting a CEL with 02 sensor(s) code. She's the type that absolutely FREAKS OUT when she gets a CEL even if it's not a dire issue. I replaced them with aftermarket units. A week or two later she gets a CEL again - this same CEL about the 02 sensor wiring.

I changed her oil today and spent some time digging around inspecting the wiring and can't find any faults. The 02 sensors came with the wiring harnesses, but I also tried to inspect the body side wiring and couldn't find any faults/cracks/corrosion (but then again I didn't bother to cut the sheaths all the way up to inspect ALL of the wiring).

Is that all I should be looking for? I mean, I find it odd that wiring would suddenly go bad. So the consensus is that this is likely due to the aftermarket sensors? Also, how exactly would I check the new (aftermarket) sensor?

That sucks because I got a really great deal on them on RockAuto wholesaler closeout and I don't want to dump much money into this car. I'm sure OEM sensors are ~$100 a pop though, eh? Anybody have a recommended discount OEM online parts site?

Hate to bump a semi-old thread but I need to re-visit this issue on my mom's 2000 Elantra.

Reibe - did you ever figure this issue out and, if so, how did you go about checking the wiring? Or did you just end up using OEM sensors?

It looks like the OEM sensors can be had for about $70-75 each.