ECM Codes
4-cylinder GM - AC Delco MPFI

The following is a list of all possible trouble codes for 4-cylinder Esprits with Multi-Port Fuel Injection:  
12 - Diagnostic Mode Enabled
13 - Oxygen Sensor; Open Circuit
14 - Coolant Temperature Sensor Circuit; High Temperature Indicated
15 - Coolant Temperature Sensor Circuit; Low Temperature Indicated
21 - Throttle Position Sensor (TPS) Circuit; Signal Voltage High
22 - Throttle Position Sensor (TPS) Circuit; Signal Voltage Low
23 - Mass Air Temperature (MAT) Sensor Circuit; Low Temperature Indicated
24 - Vehicle Speed Sensor (VSS) Circuit
25 - Mass Air Temperature (MAT) Sensor Circuit; High Temperature Indicated
26 - Quad-Driver (QDM) Circuit, Secondary Injectors
31 - Baro Sensor Circuit; Signal Voltage Low or High
33 - Manifold Absolute Pressure (MAP) Sensor Circuit; Signal Voltage High
34 - Manifold Absolute Pressure (MAP) Sensor Circuit; Signal Voltage Low
35 - Idle Speed Error
41 - Engine Speed Signal Missing
42 - Electronic Spark Timing (EST) Circuit
43 - Electronic Spark Control (ESC) Circuit
44 - Oxygen Sensor Circuit; Lean Exhaust Indicated
45 - Oxygen Sensor Circuit; Rich Exhaust Indicated
51 - Mem-Cal Error
53 - Battery Voltage Too High