I have 1995 Dodge Neon (automatic). Lately, after long trips and on the highway the “check engine” light will come on. Then, the car seems to struggle shifting. I will be cruising along at like 68 MPH, then ease my foot off the gas to slow down, and the engine/car awkwardly jerks 2-3 times as it slows down. Trying to stay in the 60-70 MPH range is hard because is keeps hesitating and jerking as my speed changes, not HEAVILY but enough to make driving unpleasant. My cruise control stopped working about a year ago, I have not had it looked at yet, but I thought I should mention it. When I let the car rest overnight, the light goes off, and there is not problem until I go on a long trip again (around 200 miles.) This only happens at higher speeds, around town there is not a problem.
Your first step must be to obtain the OBD error codes stored in the car’s computer. Fortunately, you can do this yourself, in your driveway, without any special tools or any experience.
To read any OBD codes, perform the following sequence.
Cycle the ignition key ON-OFF-ON-OFF-ON within 5 seconds.
Count the number of times the 'Check Engine' lamp on the instrument panel flashes on and off. The number of flashes represents the code. There is a slight pause between the flashes representing the first and second digits of the code. Longer pauses separate individual codes. For example, flash-flash-flash [pause] flash-flash represents the code 32.
(To cycle the ignition key ON means to turn it only as far as it takes to get the dash lights to respond. It does not mean to crank the engine.)
Report the codes here and we can advise you further.
My guess is the check engine light is a misfire fault, and if that is proven to be the case I would then start by testing the ignition coil, and spark plug wires by checking the ohms. If the spark plug wires, or the primary/secondary of the coil is out of specification then replacement is needed.
Ok - I checked it twice because it was a long number, but here is what I got and verified:
By the way, that is the coolest thing I have ever learned about my car. Thanks. Does that code mean something?
Well done. Your codes are 12 - 14 - 21 - 55. On your Neon, we disregard the 12 and 55 codes as meaningless. The code 14 relates to the MAP sensor and the code 21 relates to one of the two oxygen sensors. So now what?
I found this information regarding Neons:
"My Check Engine Light is showing codes 12 and 21. What’s wrong?
“Codes 12 and 21 (from the OBD II diagnostic check) are a common occurrence. These codes seem to appear when the electrical system voltage drops sharply for a very short period of time, such as when lifting suddenly after wide open throttle, or if the engine stumbles momentarily. If the car is running normally, there is likely no problem and the codes should disappear by themselves after a dozen starts or so. If there is a problem, the PCM will keep the CEL lit.”
This information is informative but does not suggest a useful repair action. Considering the age of your car and its low book value, I suggest you simply live with the problem and try to adjust your driving habits, rather than take it to a mechanic who will be stumped and will try to replace everything within reach at major expense. Do this and you are likely to get many more years of driving life out of your Neon. These are very durable little cars.