1998 Dodge Neon, check engine light codes. What do they mean?

The proper method for a post 1995- OBD I system..OBD II...is to use a scan tool to get the correct codes. On some models , you can do the key on-off cycle and read the stored codes on the odometer although they are more general codes than using a scan tool. A scan tool can also reset the codes whereas the key method cannot.

http://wiki.answers.com/Q/How_do_you_view_computer...

Code 12 just means the battery was disconnected or PCM fuse blew/was disconnected at some point.

Code 31 indicates a problem with the evaporative emissions system...purge valve or solenoid or hoses/wiring issues.

Have a shop check the purge valve/solenoid hoses for cracks/splits/unattached and wiring/connections at the solenoid...may need a new solenoid or purge valve...fairly cheap.

http://forums.neons.org/viewtopic.php?f=1&t=248885...

There is no sure way to tell until you bring the car to a knowledgeable technician. If your plan is to have "internet people" diagnose your car & then bring it to the mechanic and tell him what to do, you are doing little more than chasing your tail. If you do this, the mechanic will not check the car; he will just install what you tell him to. Pay for the expertise. Throwing parts at your car in hopes of fixing it is not a very smart plan. Normally you end up costing yourself more money. Also, it looks like you're listing OBD1 codes. The Neon started using OBD2 in 1994, 2 years before it was federally mandated. The 31 code pertains to the gas evaporative system. Possible causes: evap purge solenoid defective, evap vent solenoid defective, short or open in the wiring circuit, defective pcm, plus numerous others. A trained tech will figure it out in no time.

Seeing as I don't know what the "key dance" is and seeing as the codes you posted here are not the normal codes you would see with a 1998 vehicle(which uses OBDII) and gives you codes like P0112, I have no answer.

A guess would be, the first one says you disconnected your battery in hopes of the light going out and you did that just a little while ago.

The second has something to do with you fuel evaporation system.

Trying to go cheap on vehicle maint is an expensive mistake.

Take it only to Chrysler.

“Quick lube shops competing for your business cave into pressure for bargain oil changes.

“To cut costs, they might buy single weight oil in bulk or use recycled oil. They use cheaper, less durable oil filters.

“Low-wage, inexperienced technicians sometimes make servicing mistakes when trying to work faster.”

[No diss to good, independent mechanics.]

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http://www.schleeter.com/oil-sludge.htm

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“…independent mechanics complain they lack the proprietary tools and data to service many late-model cars…” some 2004 models and earlier.

They’r seeking a “Right to Repair” law allowing them access to manufacturers’ databases.

Wall St Journal, Feb, 2011.

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http://online.wsj.com/article/SB100014240527487035...

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Toyota & Ford withhold Technical Service Bulletins from customers & National Hwy Traffic Safety Admin [NHTSA]

"Automakers can save money if owners don’t know about service campaigns that include extended warranties," consumer advocate Clarence Ditlow said.

Toyota alleged it wants to “protect its intellectual property” by withholding the bulletins.

Ford alleged it wants to protect its customers from the risks of do-it-yourself repairs using info in the TSBs. But Ford sells the TSBs to commercial distributors like AllData who resell them w/o restriction.

Mercedes refused to comment on its policy of releasing TSBs in their entirety to the public & govt.

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http://www.nytimes.com/2011/04/03/automobiles/03CO...

that is an emission control problem. it might effect your fuel economy but it should not effect anything else. type the code in and you should get solutions to the issue.