[Gary Kline]

Hello All,

I have been experiencing some electrical issues with my Jeep, 19 3.2L. My Start/Stop has been disengaging and saying that it is unavailable and new this week is my Service 4WD light came on, but would go off. Been digging and searching then the check engine light came on. It was throwing code P0390, which is the Camshaft Position Sensor Circuit - Bank 2 Sensor 2.

Does anyone know where the camshaft sensors are and which one is which?


Thanks

Hi @jmy5263 ,

Welcome for the Forum!

I second @Flybynightcru 's recommendation. You have three different systems involved in those issues; (1) Electronic Stop/Start (ESS), (2) the 4WD system and then (3) a camshaft sensor which is an internal engine component error. These are three mostly unrelated systems outside their electrical-component aspect. A weak/on-the-way-out battery in a Cherokee with ESS can cause all sorts of spurious, intermittent errors that don't necessarily seem to have a logical pattern such as the ones you're experiencing. As @Flybynightcru mentioned, first step is to rule out a battery (or potentially one of the ground straps) being the root cause of this. If the errors remain once the battery is confirmed good, then I would start looking at other potential problem areas.

• Note that while camshaft position sensors can fail, it's uncommon. Many times this code comes up, people replace the sensor but the code stays and /or comes back. This is due to that code being thrown even for non-camshaft sensor issues. For example, not enough oil pressure can throw a camshaft position sensor code in addition to the weak battery issue described above so while it's cheap enough to replace the sensor (bank 2 sensor 2 is on top-right of the valve cover nearest the radiator (front of the car), there's a good chance the actual issue lies elsewhere.

Question, have you ever had 4WD issues in the past or is this the first time you've seen that error light?

 

[Gary Kline]

Already had it tested and its strong.

Your Cherokee has a bunch of braided grounding straps. If doing a quick visual inspection, do you see any green corroded grounding straps?

 

[Gary Kline]

This is the first time im seeing the 4WD light. Oil seemed fine too. Battery was tested and is strong.

So while anything is possible, it's less likely your 4WD system physically developed a problem at the same time as your CPS code came up.

Can you confirm your key ground straps don't look too corroded? Per the diagram below, there's one in the front of the engine compartment (coming off the battery lead going to the body) and then another you'll see attaching to the transmission (if memory serves me, best way to see this might be by peeking through the driver's wheel well, possibly removing the wheel liner screw in the photo below and lightly pulling back on the wheel well liner to get a good look.)

Also, now that you mention you have a 2017, you have an intelligent battery sensor (IBS) off your battery terminal that could possibly be bad. There's other folks on the Forum more knowledgeable than me on this item (I have a 2014 Cherokee pre-IBS). Perhaps search the forum for "IBS' and your symptoms and see if there's other correlating posts.

 

[Gary Kline]

Does anyone know where the camshaft sensors are and which one is which?

Hi @jmy5263 , just also to answer your question about where the CPS's are, there are two, one each on each head cover. The rear one (bottom photo) is Bank 1. The one in front is under a foam pad and is Bank 2. This is the one your code mentions. The one physical sensor has two elements in it and each element is called a sensor; Sensor 1 and Sensor 2.

 

[Gary Kline]

Mark_ its holding at 14.2-14.4 Volts. I do not think its a battery issue, as I have just replaced the battery, but you can always get a bad battery. Will have to check this at AutoZone.

Gary, thank you for the diagram. I am assuming thats the 3.2L?

Yes, it's the 3.2 V6.

 

[Gary Kline]

How do you replace the Sensors? Is it a bolt then twist?

Thanks. I didn't realize (or see ?) you had the battery replaced, sorry. The 14.2-14.4V numbers are alternator output though, not battery numbers per se, and you would get those same numbers no matter how good or bad the battery is. You are right tough, defective batteries do exist.
And since you had the battery replaced recently, another issue could be a loose battery connector ; they have to be on tight or else weird things can and do happen.
Which battery did you get ? Just curious..

@jmy5263 , yes, loosen the center bolt and then it pries/twists up and out. Installation is just the reverse. Note, you need to remove the upper air intake to get at the sensor to do the job though. There's lots of videos on YT for that. Do please however just doubly-confirm the battery /connectors as @Mark_ mentioned. While CPS's do fail, they often throw a code for tons of other things too so can be a red herring.

@Mark_ , since @jmy5263 mentioned ESS problems, could the IBS account for this or not really?

 

[Gary Kline]

Yeah, hmmmm. I haven't seen an IBS responsible for such symptoms, not that I remember anyway. These symptoms sound like voltage related, so ruling out a bad battery was #1. Loose connectors is #2. It's a 2019 so corroded grounds straps is pretty much ruled out. Next, I dunno...

Oh, good catch, I thought it was a 2017. My bad... I learned to read at at the Duralast class at AutoZone 😂

 

[Gary Kline]

Looking over the engine and found some oil underneath the filter cap. Would low oil pressure be the cause?

For the CPS code, it could. Here's why...

The Pentastar engine throws CPS codes for basically anything engine-related it doesn't like. This is why many times people get that code, change the sensor and it doesn't fix anything and the code remains. So just because the code says CPS, doesn't really mean the issue is with the sensor. The problem really lies elsewhere.

One of the things about the Pentastar engine is that it relies on high-pressure oil for the VVT (cam phasing) system. If there's not enough oil (e.g. the oil level is low) or the oil is loosing pressure somewhere, then what happens is the VVT system can't get enough oil pressure to adjust the timing the way the ECU is commanding it to do and since the sensors monitor timing, they see the timing as "off" from what's been commanded and throw a code.

Now, question...

• Where do you see the oil? In the valley (V) beneath the oil filter/cooler assembly? Can you take a photo (yes, it will be dark down there, get as much light as you can). Also, how much oil do you have in there? The lowest part of the valley is on the driver's side. When the oil gets too high, it will run out of the "V" down the back side of the transmission. Do you see oil there? (or under your car). if you are loosing oil pressure here, it could throw the CPS code but you'd need to be having a pretty significant leak. Can you confirm what you see? Photos are always the best. Also (very important), check your oil level [from the dipstick]. Are you low?

There are other oil-related things that can cause pressure loss (e.g. the oil galley control bolts under the valve covers) but that's a larger job and conversation.

One thing however, even with a leaking oil cooler potentially explaining away the CPS code, it doesn't account for your ESS or 4WD lights which I agree with @Mark_ , seems electrical/battery-related.

Thoughts?

 

[Gary Kline]

I like battery stuff, what can I say. Guru ? Ok... nah, just highly motivated to get involved
These battery connectors are poorly designed and easily undertightened. Loose, they can create all kinds of problems.

I'd say guru is accurate Mark, I think I'll be coming to you for new batt. advice before the end of summer. In the last 2 months I've seen my voltage dip below 14v for the first time (13.6-13.9) and the other day, I got my first "Batt Low" message ever (at 13.6v). My battery is 3 yrs old (wet-type) and I think the heat of this summer is slowly killing it 😢

 

[Gary Kline]

If you do end up needing a battery, and you're not like me and want the "biggest, baddest battery money can buy", I would recommend that H7 AGM from Walmart. I know you don't "need" an AGM, but I would want at least a standard OEM replacement AGM, and that what this one is for $179. It's even got the same 4yr free replacement warranty that a Northstar/X2 Power has for half the price. You can't beat that...😉😎
Robot or human?

I'm normally always go the cheapest I can find but I learned with a battery, middle of the road is better because cheap = dies on the coldest day of the winter 🥶
I'm going to get a batt. health report as Mark mentioned next time I'm @ AZ or AdvAuto so at least I'll know where I'm at before it goes... !