Created By:	Frank Mitchell	Category:	ECU / Computer / Diagnostics
Date Posted:	02-14-02	Views:	5366
Title:	Check Engine Light Fault Codes and What They Mean
Article:	If and when the check engine light illuminates you need to know what and where to go to find and correct the problem. Here is the slightly shortened version of the information. Please contact the Forum for additional information. 1. In order to determine the fault code(s) first you have to gain access to the ALDL connector. This is located under the kick panel on the right side of the car near the passenger’s right foot. Remove the panel and find the connector with the clear plastic cover and three terminals. Using a straightened paperclip you jumper between the #1 and #3 terminals (the outer ones). 2. Now turn the ignition key to the ON position but DO NOT start the car! 3. The ECM will now display a Code 12 by flashing the Check engine light. This is displayed as a flash, pause and the two flashes. This will occur three times. After the third Code 12 display the other codes will flash. Each will be displayed three times then it will move on to the next code, if any more are stored. This will continue until all codes have been displayed, then the code 12 will be flashed again. Write down each code as it is displayed so as to not miss any or try to remember them. If you should happen to miss a code then all that is needed to do is turn the key off and back on again. The sequence will begin again. The codes and their circuits or systems are listed below. CODE CIRCUIT/SYSTEM Code 12 No distributor reference pulses to ECM (one flash, pause, two flashes) Code 13 Oxygen sensor circuit (unheated type) (on flash, pause, three flashes) Code 14 Coolant sensor/high or low temp (one flash, pause, four flashes) Code 21 Throttle position sensor/voltage high or low (two flashes, pause, one flash) Code23 Intake Air Temperature(IAT)sensor circuit (two flashes, voltage high or low pause, three flashes) Code24 Vehicle sensor speed circuit (two flashes, pause, four flashes) Code 32 EGR (Exhaust Gas Recirculation) (three flashes, pause, two flashes) Code33 MAP sensor voltage too high or low (three flashes, pause, three flashes) Code42 Electronic Spark Timing Circuit (four flashes, pause, two flashes) Code44 Oxygen sensor indicates lean exhaust (heated (four flashes, type) pause, four flashes) Code 45 Oxygen sensor indicates rich exhaust (four flashes, pause, five flashes) Code 51 ECM or EEPROM (five flashes, pause, one flash) ***To remove all codes from the memory, remove the battery voltage for ten seconds (10 sec).