Description of EEC-IV DTC Code 121, 124 or 125
DESCRIPTION of EEC-IV DTC CODE 121, 124 or 125When DTCs 121, 124 or 125 are set in continuous memory, the technician is directed to the workshop manual. In addition to workshop manual procedures, the technician should refer to the diagnostic instructions supplied below.
This "In-Range" self test identifies in-range concerns of the following components.
^ MAF Sensor
^ TPS
^ Fuel Delivery System
The PCM uses information from these components and the vehicle load to generate three (3) independent values. These values are continuously monitored by the PCM. If, during normal driving conditions, one of the three values differs significantly from the others, a Continuous Memory Diagnostics Trouble Code (DTC) is stored.
EEC-IV, OBD I, Codes 124 and 125 are a result of the given air flow and the TPS sensor signal (throttle plate position).
These codes are designed to set while in the part throttle drive mode and often are accompanied by the MIL light flashing until the condition is corrected.
NOTE:
Duplication may be difficult for the following reasons:
^ Long drive time required for the PCM to calculate the error in the system.
^ Source of the problem may be intermittent.
Refer to the workshop to identify the root causes of these codes and the appropriate repair procedure.