Honda original Denshigiken manufactured ECU 37820 PT3 A51 Up for sale is a Working, in excellent condition Honda Accord ECU. Should fit 1990-1991 Accord models with 37820 PT3 A51 units- perhaps others as well. See part numbers at the top of the listing. - . This unit offers a 30 day functionality warranty. These located on the passenger side, under the metal panel just under the passengers foot area toward the front of the car.As always with this type of component your best bet is to match the part number to the one on your original ECU. Located under the passenger seat. A faulty ECU is one of the most common no start or random stalling problems with these cars. These can also cause issues with erroneous check engine lights, idle control problems as well as emission control & cold or hot start problems. I have also seen fuel pump relay turn on faults (ECU won't turn on the fuel pump), as well as an condition where the high speed injector driver has failed. This causes the car to sit and idle fine, but it won't accelerate.If your car does not have these issues but you intend to keep it a while, I recommend our customers keep an extra ECU in the trunk. These units now have to be special ordered from most dealers new for big $$ (often times over $1000!), and you can never find one when you need one. Even now finding a good one second hand is getting to be quite difficult as these cars get older.