RomRaider

1. Start a thread at NASIOC



Actually, that won't help at all. This approach works much better:

1. Get Learning View and use it to read the Diagnostic Trouble Codes (DTCs).

Click here to get a copy of Learning View. Make sure the DTC reader is enabled (there's a check box in the lower right) and click the Connect button at the top.

DTCs will be listed at the bottom of the window. The "temporary" DTCs are the ones that are causing the CEL to come on right now. The "memorized" DTCs are codes that happened in the past, haven't caused much trouble lately, but should still be investigated.

2. If the code description shown in RomRaider doesn't provide enough information, type it into the search engine of your choice, and see what comes up.


Usually you'll find forum posts from people who had that problem and fixed it. Whatever went wrong with your car, there are probably hundreds of people who have had the same problem, and a few of them have probably written about it on one forum or another. Many of the DTCs are shared by different manufacturers, so you might even find useful posts on Toyota or Ferrari forums.

(Actually a Ferrari never gets a Check Engine light. Instead, a factory technician knocks at your door, apologizes to your butler for interrupting dinner, and asks if this would be a convenient time for him to work on your car for an hour or two.)

There are a couple of sets of DTCs that tend to happen frequently, so I will describe them here.

If you just finished installing a downpipe or turbo-back exhaust, you will have these codes:

P0420 - Your cat doesn’t work as well as it should. Or you removed it.
P0244 - You’re overboosting because now you need a tune.

If you just reflashed your car, and accidentally left your reflashing connectors joined, you will have these codes, even if your VSS, start switch, netural switch, and O2 are all in perfect condition:

P0500 - Vehicle Speed Sensor (VSS) not working properly
P1518 - Start Switch Circuit Low Input
P1590 - Neutral Position Circuit Switch High Input
P0131 - o2 Sensor Low Voltage (Bank 1 Sensor 1)
P0132 - o2 Sensor Circuit High Voltage (Bank 1 Sensor 1)

See also: http://www.romraider.com/RomRaider/Chec ... LightCodes

Fantastic post. Thanks!

I should add that if Learning View isn't readily available, most auto parts places will let you borrow a code reader to scan your ECU in the parking lot. It only takes a few minutes, and it will tell you the OBD2 codes for whatever went wrong.