The dreaded CEL (check engine light)

[RobEB717678]

As I posted in the introduction forum, I have a 2009 Ram with 5.7l Hemi. It is new to me as I have only had it for less than a year. It has now 75k on it, bought it with only 71k on it. It has had one oil change (earlier this month) since I got it and the only mod I have done to it is the oil catch can.

Back in March of this year, my gf and I just finished at the grocery store and gas station (filled the tank), were going to run other errands when the CEL came on. No issues with the engine (no knocking, sputtering or other such things), nothing seemed off when checking the pressure and temperature gauges. Drove home, and asked my neighbor for his OBD scanner the next day. Checked the codes and got P0524, P0171 and P0174 errors. I cleared them out and cleaned the MAF sensor and throttle body. Check the vacuum lines and checked the oil for low levels. But nothing seemed substantial as being an issue, granted possible electrical and not mechanical. After I did the things above, a few months later I purchased a catch can and installed it. A few weeks after that, I had the only oil change done to it since I purchased it.

Yesterday, my gf and I were in the back country, mainly on paved roads, exploring and enjoying the day off work. We stopped in a country town, got gas and a late lunch. Started our travel back home and while on the road, the CEL came on. Again, no sputtering, knocking or anything) Just driving as normal. Came upon an Advance Auto Parts and asked for them to scan the codes. Came back with the same codes, P0524, P0171 and P0174. I did some research and found that a lot of the earlier 5.7l 2008 and older had issues with the ECM for the P0524 and needed reflashed. Is this something that the 2009 need as well? Not certain of the P0171 and P0174 and thinking of starting at the fuel filter.

It is just weird that all three would come up at the same time. Any thoughts of where to begin or what might be the cause of all three codes would be appreciated. Thank you, Rob

 

[RobEB717678]

Add a little more, I looked into the fuel filter replacement... Think I will hold off until I know for sure it is the issue. On another note though, the CEL turned off today on its own. Did some errands around town and got in it and the check engine light was no longer on. Could it be related to a full tank of gas? Both times previous seem to happen after filling the tank.

 

[OCDTech]

Weird how the lean codes are teamed with low oil pressure code. If theres any way you could check fuel pressure both idling and driving and make sure its in spec. As for the low oil pressure try changing the sending unit maybe, shouldn't be an expensive part. I see where this must be something that happens. I see several write ups on it. Do you have a scan tool with live data capability. A dongle usually 20 dollars or so and an app on a phone and you could watch fuel trims as you drive to see if and when this lean condition shows itself. Don't see how filling the tank could cause this.

 

[vwmaniaman]

I read somewhere that if you pump in more gas after the pump shuts off you can flood the charcoal tank and get weird errors.

 

[SYKRAMMAN]

Yeah that sounds like an issue with the fuel tank vent tube. There’s been a few people on here that have had issues only after filling and topping off. Not sure what the fix is. Check some of those threads out.

 

[VB712]

I don’t ever top off my tank. When the pump stops I’m done. Heard stories of people having issues from doing so.

 

[NCRaineman]

I don’t ever top off my tank. When the pump stops I’m done. Heard stories of people having issues from doing so.

It's generally OK to round out your purchase to the nearest dollar after the pump kicks off, but I certainly wouldn't go trying to cram another gallon or two in there.

 

[RobEB717678]

I can honestly say, I’ve “topped off the tank” a few times and ended up with gas fumes in the cab and around the truck after the top off. So I no longer do that and both times that I got the error codes, I didn’t top off the tank. Once it stops pumping, that is it, no more. I will do the research on the forums for the issues being part of the filling of the tank. I looked at one last night and it seemed to be a tether thing with the gas cap and mine doesn’t have that. Previous owner must have removed it. I might buy a new gas cap all together and see if it stops the issue but it comes on so randomly and so few that it is hard to gauge what is the root cause.

I have used my neighbors doogle to help with the codes which is nice but I would like to look into getting one of my own, especially one that give real time stats, kind of like what OCDTech suggested. Any suggestions?

Also! One last thing, I started to pay attention to the instrument cluster yesterday just to see if I noticed the oil pressure drop. Before the CEL turned off, I noticed that at times, especially when in motion, the display in the middle would dim a slight bit and when I used the right turn signal it would also dim. But after the CEL turned off, the display would not dim any more. Is the oils pressure sending unit, O2 sensors and the cluster on the same terminal connector to the ECM? Could it be a lose connection?

 

[NCRaineman]

You can get an OBD2 code reader from Amazon or Wish for pretty cheap... there are also more expensive ones that will do data logging and that kind of stuff as well, just depends on how much you want to spend.

The little tether for the gas cap is annoying and will break off after a while. I have to fiddle with mine at every fill up to make sure it's not getting pinched by the cap or the fuel door, there's not enough slack in it for it to tuck away properly when you reattach the cap.

 

[OCDTech]

I can honestly say, I’ve “topped off the tank” a few times and ended up with gas fumes in the cab and around the truck after the top off. So I no longer do that and both times that I got the error codes, I didn’t top off the tank. Once it stops pumping, that is it, no more. I will do the research on the forums for the issues being part of the filling of the tank. I looked at one last night and it seemed to be a tether thing with the gas cap and mine doesn’t have that. Previous owner must have removed it. I might buy a new gas cap all together and see if it stops the issue but it comes on so randomly and so few that it is hard to gauge what is the root cause.

I have used my neighbors doogle to help with the codes which is nice but I would like to look into getting one of my own, especially one that give real time stats, kind of like what OCDTech suggested. Any suggestions?

Also! One last thing, I started to pay attention to the instrument cluster yesterday just to see if I noticed the oil pressure drop. Before the CEL turned off, I noticed that at times, especially when in motion, the display in the middle would dim a slight bit and when I used the right turn signal it would also dim. But after the CEL turned off, the display would not dim any more. Is the oils pressure sending unit, O2 sensors and the cluster on the same terminal connector to the ECM? Could it be a lose connection?

The app i use is Torque, there is a free one and a 5 dollar one, not sure of the differences, only thing is they do not have iphone support as of yet, only android. But there are several more to choose from. As for your issue with the dash dimming etc, while reading other threads on phantom things like this it seems people are finding wiring connectors corroded, tough to find sometimes. My dongle i use is BAFX with bluetooth, works good. But any ELM 327 will work probably, just stay away from cheap chinese ones hear they aren't that good.

 

[SYKRAMMAN]

Now it’s sounds more like a electrical gremlin is running around your truck, check all your grounds make sure they are clean, no green ooz or crap on/in connections.

You can get a decent Autel mx808 for around 400$ and that does most of what a dealer can do except programming/flashing.