Check engine light

[BillO]

Gentleman,
I have a 2019 Ram 1500 Laramie with 110k miles… just had an engine light come on. Mechanic buddy said it’s an EVAC sensor but couldn’t be for sure, saying the code was vague. We swapped a solenoid, cleaned the fuel lid etc… but the problem remains. I’m being told it’s not a serious problem but I hate having that stupid light on my dash and when the light is on the remote start won’t work…

Yeh, first world problems but has anyone else come across this? Any advice would be awesome! Thanks in advance.

 

[Tom Davis]

First question would be what code is it throwing?

 

[BillO]

I think he said it was an EVAP P0456 or 456 code…

 

[Tom Davis]

This is from a quick search.

Causes Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened.

Any of the following could also be the cause:
- A small leak in any of the EVAP hoses or fuel tank hoses
- A small leak in the purge valve or vent valve
- The EVAP Canister may be leaking

Possible Solutions:
- First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well.
- If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component.
- Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.

Hope this helps. I would start with the gas cap, it may not be sealing properly.

 

[BillO]

This is from a quick search.

Causes Usually this P0456 code is caused by an incorrect or faulty gas cap. Filling the fuel tank with the engine running could conceivable cause this code as well or if the cap wasn't properly tightened.

Any of the following could also be the cause:
- A small leak in any of the EVAP hoses or fuel tank hoses
- A small leak in the purge valve or vent valve
- The EVAP Canister may be leaking

Possible Solutions:
- First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well.
- If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component.
- Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.

Hope this helps. I would start with the gas cap, it may not be sealing properly.

 

[BillO]

Thanks for the info, this model year doesn’t have a fuel cap, it’s one of those spring-loaded covers, but I’ll try the other options.

 

[Atcer2018]

I’m my limited experience with the EVAP system on a 2018 I’ve found the P0456, small evap leak, code to be pretty much what Tom Davis outlined above. In my case the ESIM or evaporative system integrity module is the second part to check after the gas cap. While you don’t have a gas cap the sealing mechanism on the newer models still needs to be working correctly. I have no practical experience with this type of sealing system aside from my wife’s Ford has it and it’s nine years old with no issues so far. The ESIM also called the “charcoal canister purge valve” although it’s not the actual purge valve on Ram trucks. The ESIM is activated by the ECM to vent stored vapors into the intake manifold to be burned in conjunction with the actual purge valve which is up in the engine compartment under the engine beauty cover on the passenger side. Either one of these valves are suspect although the one in the engine bay is less suspect than the ESIM. The last culprit is the charcoal canister vent filter. It’s a pleated paper filter inside the driver side rear wheel well and if your truck has wheel well liners, yes it’s a PITA because that liner needs to be removed to get to it. Luckily none of these filters or valves/solenoids are more than $50 each. The one in the engine bay is easily accessible. The ESIM is a bit challenging but you can still get to it from under the truck with little patience. The filter is not hard to access but does require removal of the wheel well liner. I’ve attached a pic of the ESIM location on the fuel tank and a crude pic of the vent filter. Since you have a mechanic it’s best if he tests the system out to determine what’s at fault before firing the parts cannon at the code. Hopefully he has a emissions smoke machine to track down the leak although I doubt a 2019 would have a faulty hose yet. Good luck.

 

[BillO]

That’s great info with good instruction. I’ll start checking and I’ll update with the outcome. Thanks!