Greeting. 2004 Liberty, 3.7 6 cylinder with 62,000 miles. New platinum plugs, oil change, pcv valve @ 60,000. Shortly after purchase of this vehicle at 60k and a solid pass at the smog station, the OBD started kicking up a P0158, which is a o2 sensor, bank 2 downstream. (Pass side after cat)
After purchasing a new sensor and replacing it and resetting computer, no luck and same code. To ensure that the new sensor was not bad, I removed the driver side sensor downstream and used it in place of the pass side sensor. Same results after resetting the computer. (battery disconnected for 30 minutes).
Can of SeaFoam in the gas tank. No change. Then magically 500 miles later, light went off. Light off lasted several days and now it is back on and kicking up the P0158 code again along with a new code, which is P0161.
Is this an injector issue? Engine seems to run okay with no noticeable problems. I have been tracking gas mileage and libby is getting 17mpg average. I did read somewhere that the libby's like copper plugs, not platinum. Could this be a problem?
Any ideas before I have to mortgage the farm and take it to the Jeep dealer?
Well, a few things to start. Platinum plugs arent required, and sometimes cause running issues on the 3.7L. Standard NGK copper plugs are OE, and are all that are required to make it run like new. The bosch O2 sensors that the parts stores tend to push are borderline garbage. NTK, or OE on the sensors. You swapped the sensor and it didnt follow it, so the problem is confined to bank 2 on the p0158. You learned an expensive lesson, that the code doesnt always point to whats bad, just at what is reporting bad data, two entirely different things. A p0158 says that bank 2 post cat was reporting high voltage, or rich condition after the cat. P0161 points to the heater circuit and excessive current draw. Did this happen after you swapped the sensor to the other side? If so, you have a problem with the bank 2 rear O2 sensor now as well. Theres a few things that can cause that code, some of which are injector issues, but also the front O2 sensors as well. Also worth noting, seafoam is about worthless for cleaning. Yeah it makes a pretty smoke out the tailpipe, when its injected into the intake, but it will do this on a clean new engine. Its the chemical burning, not the gunk being burned out.
Thanks for the response. I was able to take the Bosch sensor back to the dealer because it already had been opened and looked as if it was previously installed in a vehicle. I made a note of this at purchase, and they said if it did not work out for me, just bring it back. So no lost money there.
The P0158 originally popped up a few days after I changed the plugs. I had to order the PCV valve since it was out of stock so did not change that right away. After the P0158 popped up, I changed the PCV and a day later the light went out on its own. Great I am thinking, cheap fix. But then a few days later the light returns with the P0158 code showing up again. That's when I ordered the Sensor and installed it. After resetting the computer the light did not go off still showing a P0158. That's when I thought the Bosch sensor was bad. So I pulled it out completely and put it in its box for return.
So to confirm that the original jeep sensor was defective or not, I pulled the driver side sensor and installed it in the pass side, and took the pass side sensor and installed it in the drivers side. I was told that both post sensors (sensors after cat) were the same.
Well after I did that and reset the computer, the results were the same. P0158. This told me that the sensors were both okay. After that I did the seafoam. Light went out a few days later only to return in a few days with the P058 code and the additional P061 code.
I think I am correct that both the P0158 and P0161 refer to the second sensor (downstream of cat) on the passengers side? Am I correct on that?
Since this all started happening after I changed the plugs, I think I will replace the platinum plugs with the original NGK Copper plugs and see if that fixes the issue.
Any other suggestions please. I just purchased this Liberty after my Cherokee was rear ended by a young lady texting on her phone. I was hit at 55mph and she never touched her brakes. The Cherokee took the hit well, but was totaled. I had to be cut out of the Cherokee since the rear doors overlapped the front doors and would not open.
I love Jeeps and there was no question I needed another. Being born in Toledo where the Jeep factory is has nothing to do with it, lol.
Thanks for your response and please give me more ideas.
Yeah both codes refer to B2S2, bank 2 sensor 2. One code is saying the pcm does not like the data it is reporting, the other code says it doesnt like the heater circuit load, according to a quick google search. With the p0161, I would question the O2 sensor located there. THe p0158, you could have wiring issues, which could relate to the p0161 as well. Could also have a issue upstream as well. Little more diagnostic time is needed to confirm. You could use a multimeter and measure the resistance of the heater circuit of both rear sensors. A large difference would definately indicate a problem. Also, if these codes are cleared properly, then they should not show up immediately after clearing them. If they arent, then either the code clearing wasnt done properly, or there is another problem. Some reason, the signal side of the B2S2 O2 is reporting high voltage at times, and looking at the freeze frame data thru a scan tool would likely tell alot more to the story.
Well I ran out to the local auto shop and bought the NGK Copper plugs. I no longer had them in the libby for 5 minutes (not installed, just sitting on the seat), and the friggin light went off. I drove to the store, and then home and it is still off. Quite interesting to say the least.
Do you know where the harness comes up the firewall from the passengers side? I'll take a look at that next to see if it is damaged anywhere. Is it possible to pull it out to inspect it. Is seems like a tight fit from under the vehicle.
Not sure what is causing your code, but I was told by a local Jeep mechanic
" Do Not Use Bosch Platinum Plugs, Mopars don't like them. "
He said that he has pulled Bosch plugs out of many Mopar products to clear up weird codes. Autolite Platinum were OK. otherwise use copper.
I used the Autolite Platinum 6000 miles ago & had no problems
Okay, here is the latest report. Have not replaced the plugs yet due to a bad cold. But the light has now gone on again, off again, and now on again with the same codes.
Here is my question. If the computer is not reset, will the light and codes just go away if the problem fixes itself? If the answer is no, then it must be a short in the wiring to that sensor, because I have not reset the computer between the light going off and on again.
What do you folks thing about the short in the wiring theory?
Thanks and one more question. Are we having fun yet? I'm not, lol.
You can have a part that has an intermittant problem, or is performing right at the limits of whats good and bad. Some codes, not all, if the OBD test passes and tests good for so many drive cycles, it will turn off the light. P0158 is one of those codes. Dont assume its wiring to that sensor, until you've done actual testing. Theres plenty of data available on a good scan tool that could help pin down the problem. If you lack the knowledge and experience, I strongly suggest taking it to a professional, rather then risk making the problem worse trying to fix it yourself.