Hyundai Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
35 Posts
Discussion Starter #1
check engine light came on the other day and it's finally warmed up enough, meaning double digits, for me to pull the codes. I got a P0150 and a P0174. A quick check show both to be connected to the front heated O2 sensor. It also said that possible bad wires could set a code. Is the sensor mentioned the one right in front of the fan shroud? If so, I think my may have been replaced at an earlier date with a non OEM one as the wires bend at a hard 90 degree angle coming out of the sensor and are against the shroud. I can see no visible breaks but that doesn't mean much. So the question is, how hard is it to pull the shroud/fan out? There isn't enough room to get a slotted socket between the shroud and the sensor to replace it otherwise. I just hope whoever replaced it last was smart enough to use anti-seize.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #5
No exhaust leaks that I can see. And acceleration and power are good with only a slight surge at initial takeoff when cold, and then only once. Red, wouldn't a bad sensor set other codes as well? P0431 is the only one showing and it wasn't there before. I drove about 90 miles before it came on.
 

·
Registered
Joined
·
8,111 Posts
My thinking is the bad primary O2 caused the engine to run lean. This masked or caused the cat problem. With the new primary O2 and the engine running with the proper A/F ratio it now overloads the bad cat.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #7
Lovely, can I change out just the cat, or do I have to change out the entire system from the manifolds to behind the cat?
 

·
Registered
Joined
·
8,111 Posts
I'm sure you can just change the cat. I would change the rear O2 first.

How many miles,and what year is the car?
 

·
Registered
Joined
·
8,111 Posts
Rock Auto has a downstream NTK O2 for $35. And the cat is $168. You can get 5% off if you use the discount code 2049289418279695 in the "where did you hear about us" blank. Good until 5/4/2014

They also have the Y pipe with the front cat installed, no firewall cat. This is 51" in length but is $368
 

·
Registered
Joined
·
8,111 Posts
It's a V6 right? There would be one for each bank and a set of O2 sensors for each bank. There may be a single cat further down stream but this is not monitored and does not affect engine performance, unless it is clogged up.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #13
Yeah, its's the 3.5 V6. I'll start with the left downstream O2 sensor and see if that helps, if not I'll have to replace the left cat. Thanks for the help.
 

·
Registered
Joined
·
907 Posts
Before starting to throw O2 sensors on the problem short and long term fuel trim numbers should be looked at as well as O2 sensor signals compared btw banks.

If possible swap the post MCC/cat O2s of the banks and see if the problem moves ...
 

·
Registered
Joined
·
35 Posts
Discussion Starter #15
I don't have access to the proper equipment to check that e3tom. As I stated in my OP the left upstream was replaced at an earlier time by a universal fit O2 sensor and the wires were kinked over hard by the barrel being to long and riding against the right cooling fan. After looking at the left downstream and it's connector on the side of the block, I see that whoever replaced it last did the same on that end as well. It is kinked over also. So far all the problems have been with the left bank. That's the problem with buying used, you usually end up fixing other people's screwups. If it does turn out to be the pre cat, I have a friend with a shop that will help as I don't have all the necessary equipment.
 

·
Registered
Joined
·
35 Posts
Discussion Starter #16
Replaced the lower left O2 sensor this afternoon and cleared the code. I'll know it the problem is fixed after a 600 mile road trip tomorrow. But I found that the old one had the tip bent and the outer mesh was compressed against the inner core. It was NTK, so I wonder if it happened at the factory. I mean, it's not like it's hard to get to the sensor. Took me all of 45 minutes, and most of that was spent figuring out how to get it disconnected from the wiring harness.
 
1 - 16 of 16 Posts
Top