Hello,

I recently purchased a 96 neon and Im trying to fixerup. Anyways, She kinda has a rough idle in that it will sound like shes going to die, but then pick back up every 3 seconds are so. Also when your driving along and take your foot off the gas, she will shake kinda bad.

I checked the codes and shes throwing a: 12, 21 and 42.

I just replaced the air filter, oil filter, oil, plugs and wires.

From doing several searches im thinking of trying to replace the Fuel Filter and O2 sensor to see if this will fix some of the problem.

Im a poor girl and would prefer the cheaper solution first if available. Does anyone have any other suggestions?

Thanks!
Colleen

 

12 is no big deal, pretty standard for a first code. Means the battery has been disconnected within the last 50 startup cyles.

21 is the oxygen sensors. There are a ton of reasons this code could pop up.

42 could be a number of things as well - fuel pump relay, ASD relay, or fuel level sender prooblems.

My suggestion is to take the car to Autozone and have the codes read for free. They will give you the 4-digit codes (i.e. P0462, etc.), and that will go a long ways in pinpointing the problem.

Here's my thoughts though... If it was the ASD or fuel pump relays, the car wouldn't start. It could be an intermittent problem, like a loose wire or something though. That leaves the fuel level sender for the code 42. Is the fuel gauge tracking properly? The upstream sensor has the biggest effect on fuel control. If that sensor goes bad, the car could be running extremely rich, which would account for idling issues and otherwise erratic behavior. However, the O2 sensors get their power from the ASD relay, so a fault there could be causing problems with the O2 sensors.

No sense replacing stuff that doesn't need it (O2 sensors aren't cheap). So once you've got the 4-digit codes, we can make a better analysis. Does your '96 have an external fuel filter? Some did, some didn't. Even if it did need replacing, it shouldn't be causing the other codes to come up. If you don't have the external fuel filter, there's no need to replace it. The external filter is located behind a removeable panel just forward of the passenger side rear wheel. Recommended repalcement interval is every 35k miles.

We're all poor, we drive Neons. Those of us that keep them become mechanics...

Best of luck!

 

Thanks for the reply. Ill check on whether the fuel filter is internal or external when I can. As for taking it to Autozone, we actually dont have one here. We just have Checker Autoparts. The gas gauge isnt reading anything. Its always at empty. I was going to try the soldering thing this weekend or someone said that maybe its not grounded.

Thanks for your help!