How do you know if your ecm is bad?

Idle air control valve is not closing properly. Check connector carefully. If it looks ok, remove and inspect installation of the valve.

replace the IAC sensor , then use a scanner to reset the ECM

code p0507 refers to idle sped control (ISC) system--rpm higher than expected==causes --wiring--isc actuator--iac valve--throttle motor--throtle valve tight/sticking--ECM
it also refers to idle air control (IAC) system --circuit low==causes--wiring short to ground--IAC valve--ECM

mechanical throttle or electronic throttle. let me know I will make you understand

P0102: you need to make sure the sensor is clean; sometimes it get dirty as you are working on an old car. Check the voltage manually. Make sure there is no air leak near it

P0507: high idle... this sounds like a vacuum leak. get starter fluid and start the car. Spray around and check for change in car idle

the dreaded P0507, have you had your throttle body cleaned lately? I did clean a neighbors TB while doing other maintenance things to it, and this popped up-and it was miserable getting rid of it. You have to do a 'relearn' procedure (about a million times or so, it seems) and DO NOT take it to a dealer-they will just charge you $100 and tell you to install a new throttle body (not cheap). They know this is a problem, and act like you have done something wrong for merely cleaning a dirty TB. It can and will go away if you do the 'relearn' procedure-read this post for information on how to fix it. it is just annoying but does not have to cost anything to correct. His took MONTHS to reset, but it did, and I did a lot of research on this and can assure you it is not what the dealer would have you think it is-they will try to separate you from your money for this code. read this:

http://www.nissanclub.com/forums/2002-2006-nissan-altima-discussion-2-5-3-5/243119-p0507-idle-control-system-rpm-higher-than-expected.html

{: ) DTC P0506 Idle Speed Low
The usual cause is an excessive carbon build-up on the throttle body. If this is the case, I suggest you have your throttle body cleaned and perform an idle relearn procedure using a GM scan tool. The idle relearn or reset procedure is very important, otherwise this code may still remain even after a throttle body clean.
In a similar fashion, if the ECM/PCM (engine control module) of a high mileage vehicle is replaced and/or reprogrammed without performing the Throttle/Idle Learn procedure, the ECM/PCM may no longer compensate for existing carbon build up in the throttle body, causing it to return with a similar concern as well as DTCs P0121, P0506, and/or P0507.
There are other conditions that can also affect or reduce idle speed by increasing engine load like incorrect torque converter clutch (TCC) operation, accessories that require additional torque to operate, restricted exhaust, and mechanical conditions that limit engine speed.

click on the below links for code details.
P0106

P0121

P0171

P0174

P0335

P0340

P0385

P0442

P0506

P0507

P0601.

all of the above codes seem to have a common cause, they all list a bad ecm (computer) as being a cause, and the last code P0601 points specifically to a bad computer. sorry for the bad news, hope this helps.

When all electrical power is removed, the car's computers are reset to a default mode. They have to 'relearn' your specific car's needs. Give it a couple of days and see if it doesn't recover. This goes for the transmission too -- it has to relearn shift points, so it may shift a little roughly for a day or two. If you still have the problem after a couple of days, have it checked to see if you have any error codes stored.