2016 Kia Rio - Check Engine Light - P0456
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Here is a list of tools I use every day at the shop. Let me know if you use them too in the comments!
Customer Complaint: Check Engine light is on and wants it off.
General Information: After looking at the code that turned the check engine light on, I knew it wasn’t going to be fun. Anytime I get an EVAP code that says “very small leak”, I know it can be anything. I have seen purge solenoids not closings all the way do this, or vent valves not closing all the way, or even actual small leaks from lines or o-rings.
If you don’t know what the EVAP system is, it is basically a system that makes sure gas vapors do not escape into the atmosphere and cause damage.
The code this Kia had was P0456.
Diagnostics: Generally when I look at EVAP problems, I start with scan tool data. Typically, if a purge solenoid was leaking, it’ll draw vacuum in the fuel tank while the engine is running. If a vent solenoid is leaking, it won’t allow a good vacuum into the fuel tank. Of course, there is more to EVAP diagnostics than that, but those are some things I look for first.
I also like to see if I can command the solenoids on. If I can hear them turn on, it gives me a good indication that the circuit is good.
BUT, just because I can hear the solenoids activate, it does not mean they are good. They can still leak.
In this Kia, nothing seemed out of the ordinary with the scan tool data and I could hear the solenoids turn on.
The next step I took was to connect a smoke machine to the EVAP system. As shown in the picture at the top of this case study.
Connecting a smoke machine to this car was fairly easy. All I did was take the hose off of the purge solenoid and connected the smoke machine to the hose that was going to the fuel tank.
It’s important to check the purge solenoid and vent solenoid separately.
I turned the smoke on and started to see smoke near the back.
There was smoke coming out of the gas cap.
Okay, I have to admit. I had a suspicion it was the gas cap from the beginning. But only because the customer stated that the gas cap started to not “click” like it use to.
I can’t stress enough how important it is to ask the customer questions to further your diagnostics. A simple, “Have you been noticing a difference in your vehicle since the check engine light has came on?”, can go a long way.
After getting a new gas cap that “clicks”, nothing leaked smoke and the car was fixed!
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