Engine light

The first step is to have the diagnostic fault codes read and recorded. The people at many auto parts stores will do that for you for free.

Hi DON HANNAH,

If you decide you would like to conduct the scan yourself here is a link to an article that features written step by step instructions and pictures explaining how to do the scan yourself. Also, I have included a link to our YouTube channel with a how to video on code scanning.

This is applicable even if your check engine light is not on.

Most scanners are inexpensive to purchase, you can purchase one online from sites like Amazon.com

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

https://youtu.be/YV3TRZwer8k

Once you have the codes please get back to us so that we can further assist you. We are always happy to help.

Thank you for visiting 2CarPros.com.

Kindest regards,

Renee
Admin

P0204 - Injector Circuit Malfunction - Cylinder 4
P0456 - EVAP Leak Monitor Small Leak Detected

Before you get too wrapped around the axle, switch the injectors between cylinder 4 and one other one, erase the fault codes, then see if a code sets for the cylinder you moved the injector to. Chrysler has extremely little trouble with their injectors, so wiring and connector terminal problems are better suspects, but this is an easy way to eliminate the injector as the cause of the code.

The only thing you can do for code 456 is a visual inspection for dry-rotted hoses and rusted hose clamps. To find small leaks in the vapor recovery system, you need a smoke machine. Typical suspects are valves with leaking seals, and cracked hoses.

Code 456 has nothing to do with engine performance. That refers to fuel vapors expanding in the gas tank, then being stored in the charcoal canister. At certain times, the Engine Computer opens the purge valve so those stored vapors can be drawn out and burned. That entire system is monitored for leaks to prevent hydrocarbons from being released into the atmosphere. Chrysler does that by pumping the system into two pounds of pressure, then watching how long it takes for that pressure to bleed off. Code 456 refers to a slow leak, unlike that of a lose gas cap.

The injector circuit code is not one I've worked with before. I only know the computer monitors the electrical integrity of the circuit, and it can read the resulting current wave forms to interpret how the injector is operating mechanically. Chrysler has very little trouble with their injectors, so given your description of the symptom, my first suspicion would be a wiring connector is being tugged on when the engine rocks during acceleration, and an intermittent break in the circuit could cause jerking or rough running. I actually had that happen to my old '88 Grand Caravan about three days after I stuffed a different engine in it. Three injectors stopped firing intermittently, but only under hard acceleration. Unplugging and reseating the plug for the engine wiring harness solved the problem.

You might be able to make the problem occur by flexing various harnesses while the engine is idling. You'll be able to hear the misfire if one injector stops firing. If nothing is found, switch this and one other injector, erase the fault code, then see if the code sets again for the same cylinder or the one you moved the suspect injector to. If the code moves to the new cylinder, it's pretty sure the injector is the cause of the problem.

The Engine Computer pumps the gas tank and fuel vapor recovery system up to two pounds of pressure, then watches to see if and how fast it leaks down. If it takes a while, a fault code is set related to "small leak detected". Those can be impossible to find without using a smoke machine to make the leak visible. If the pressure leaks down very quickly, or no pressure ever builds up in the system, a different fault code is set for "gross leak detected". The most common cause of that is a loose gas cap, and since that's an easy fix, they put a "Gas Cap" symbol on the dash. While they'are much less common, there are other things that can cause a large leak. Usually those can be found with a visual inspection.