2001 Honda Odyssey w/ Engine Check Light and TCS Light

My wife has a 2001 Honday Odyssey LX with about 110K miles.  Hopefully unrelated history, we got a new transmission at 75K due to the recall.

Over the last few months, she has experienced intermittent "Check" engine light and "TCS" light coming on (they come on at exactly the same time), but then going off on their own.  TCS is the traction control system.  This first happened while she was on a roadtrip, and by the time she got home (1,000 miles later), the lights had gone off.  It has happened again a few times in the meantime, but before she gets it to the shop, the lights are off.

The owner's manual indicates that an improperly installed gas cap may cause the check engine light to come on, and that appeared to fix it maybe once.   The manual also says the TCS light may indicate a significant problem with the brakes, but they've been "checked" by two different shops with no problem.  

The dealer checked the codes, said we needed a new EGR valve.  Sounded strange, so I got a second opinion at a local small shop recommended by coworkers.  He saw the same codes, replaced the EGR valve and followed some "bulletin" that said the Odyssey has a known issue with carbon buildup in the lines and to clear them with a drill bit or something like that.  He then cleared the codes on the computer, and the lights were off.

My wife then drove the car for 2 days, and then headed out on another road trip.  Of course, the lights came back on.  She called the shop, he said that since she had just filled the car up with gas, it might be the gas cap improperly installed or maybe the gas cap seals have gone bad.  

So I called ahead and found her a gas cap at a Honda dealer.  She stopped, got the new gas cap, and they offered to check the codes (kudos to Glenwood Springs, CO Honda dealer - very helpful to a woman on the road!) which again say the EGR valve.

Any idea what this really is?  Why would EGR valve also set off the TCS light?  

Thanks!

[discretesignals]

If there was a problem with the gas cap then there would be a code in the PCM(Powertrain Control Module) for an EVAP(Evaporative emissions system) leak, usually a P0440 or P0442.  What is the code that the PCM is setting for the EGR system?  If there is a code being set by the engine controller that affects the operation of the TCS then the TCS light will come on too.

I don't know the exact code (will definitely get it when my wife takes the car back to our mechanic), but it was an EGR code at the dealer, at the shop that replaced the EGR valve, and again this morning at the Glenwood Springs Honda dealer, not emissions.  I figured for $17 it couldn't hurt, but likely didn't help.

More details.  After replacing the EGR valve, my wife did mostly city, but a little freeway driving.  She then filled up the car this morning, got on the freeway, and the CEL/TCS lights came on within a couple minutes.  She stopped at the dealer 250 miles later, got the code turned off, new gas cap, and then filled up the car with gas and the codes stayed off for another 300 freeway miles.  She then stopped again to fill up with gas and a few miles down the freeway both lights came on again.

If I look for a code reader, what kind do I need to get?  Do they all have the same interface with the car now?  Do they all have the ability to turn codes off, or can some only read codes?  Any recommendations for a decent, yet seldom used (ie, preferably inexpensive) code reader?

[discretesignals]

You can purchase an OBD2 Global Code Scanner that will work in any vehicle that is equipped with an OBD2 style data link connector.  They arn't too expensive if you are planning on owning one.

Here is a picture of an Actron OBD2 Autoscanner that Autozone sells for around $100.  It only has the capabilities of retrieving code(s), giving you a general description of the code(s), and erasing them.

Thanks for the info on the scanner.  If it only checks the code, gives a general description, and erases codes (which sounds like a lot!!), what can the more expensive/capable ones do?

More details on the car:  My wife is still driving the car on her trip.  Per my last post, the TCS and ECL came on after filling up and getting on the freeway.  She went through a few more fillups and highway driving.  She stopped at her parents and spent the night.   After the car was turned off and sat overnight, the next morning the TCS light was off, but the ECL stayed on.  She did a couple of city trips (on/off cycles) with the ECL staying on.  She then filled up, got on the freeway, and the ECL went out.  Strange.  Any ideas?

[discretesignals]

The more expensive ones also have the abilities of erasing, reading, and giving you a description of the codes.  They also allow you to read engine data OBD 1&2, fault records, and perform special tests(such as controlling PCM outputs) on many other vehicle makes.  They also read IM flags, view run monitors, and let you look at mode 6 data. Some even have built in gas analyzers and/or DSO scopes, PCM programming capabities, and updates through LANs.  Of course, the more expensive the more options they have.

Here is an OTC Genesis fully dressed: around $5,000


There are many other companies out there offering the abilities to using a laptop to do the same things as a scan tool can.  
Here is a laptop configured to operate as a scan tool:


Here is a factory pocket scan tool that is used by Honda/Acura dealers made by Teradyne(big money/first born/left nut):