I have put about 200 miles on the car and so far everything has been smooth. the battery light has not been on and the charging system all checks out fine. only problem is i have a CEL's for p0135 and p0141 which are heater circuit malfunctions in both o2 sensors. Did Honda use different sensors from 02 to 03 which would cause it to throw a code? i know the the wiring is good because i checked for continuity before I installed the harness. These codes were not displayed on the old ecu.

 

Is 10A dash fuse 4 blown?

 

the fuse has continuity and has 12.5v on both sides with the key in the ignition.
i understand why the p0141 code is being thrown because i have yet to hook up the downstream sensor because i need to wire in the plug to the harness and the ecu still, but the upstream sensor is installed.

i may have forgot to mention that i currently have sensors for the 2002 ex ecu installed with the new 03 ecu. i believe this may be my problem.

 

I just suffered the same problem...
1. check the bolts on your alternator, if those bolts come loose and the belt slips off the serp.. it will overcharge your PCM.. and force the car into Saftey/Limp mode...

2.You'll have to buy a new PCM or used.. Install it and get your keys matched with immobilizer and new PCM.. Honda Dealer is the only that can update or program Immoblizers..

3. Look forward to spending 800$ to 1000$.

4. Inspect Alternator BOLTS!!!!!! They will Break!!!

 

I have checked every fuse, ground, wire.... in my car, it is 100% alternator...

 

Old thread.