My sons 1997 Honda Civic LX recently began running bad and having difficulty starting. We had it scanned at autozone and these codes came up. I replaced all the sensors including the Throttle Position Sensor and it still ran bad. Also replaced the Engine realy. I brought it to a local mechanic shop to have the codes scanned again and I still had the same codes. Mechanic stated that he believed the ECU was bad since the codes could not be cleared. I replaced the ECU and it has no change. Any suggestions?

rm530@charter.net

 

Those are codes for the IAT, ECT, and TPS. Are you saying that after resetting the ECU, all three codes appear immediately when the key is turned to ON(II)? How are you clearing the ECU?

 

Must be a fault in the wiring since you've replaced everything else already. Check the ground wires on the thermostat. Download the diagram and determine which ECU pins lead to the sensors. Unplug ECU and measure sensor resistance at the ECU plug and at the sensor, it should be the same, if it's not there is a bad wire. I think the two wire temperature sensors work between a 5 volt supplied by the ECU and the ECU.

 

After I had replaced the ECU I sent him to Autozone and to the mechanic shop. Both said it was bringing up the same codes again. The car will start after several cranks and he said as hes coming to a stop the jerks as downshifts. But I do have to ask this, it seems to me that this started right after he decided to go have his frined install an alarm system in his car. Could this just be coincidence? Just has me puzzled because the car ran flawlessly. its a 1997 Civic with 41000 original miles on it