A Check Engine Light can come on because some models may misinterpret the ratio of air and fuel being burned for combustion. The powertrain control module (PCM) can also misinterpret data from the coolant sensor and set a Check Engine Light. For either condition, the PCM will need to be replaced.Google+
Car Problem Reports
Honda Accord PCM can misinterpret air fuel ratio and coolant temp requiring replacement of the PCM
Honda Accord Problem
Exhaust & Emissions Affected: 2.3L 4 Cylinder
Visitor, 1998 Honda Accord, 100,514 mi
Crank no start after car sitting overnight in garage or sitting over 4-5 hours. Car will start after 2-3 attempts, but barely stays running with an extremely low idle near "0". If you give the car any gas, because it sounds like it is struggling for fuel, it will immediately die. If you let the car run in park or just put in "R" and sit in driveway for 4-5 minutes, the RPMs will increase to a "normal" idle range. Had the main relay replaced which fixed the problem for exactly 1 week, no problems starting or with idle, now back to exact same symptoms before the relay was replaced so I assume the PCM does need replacement.
Diagnostics from mechanic (Naper Auto) states that PCM/ ECU is reading coolant to be 160 degrees despite engine being cold start and PCM needs to be replaced.