There are two ways to get the codes on the 90/96 300ZX.
Here you go:
http://www.ttzd.com/tech/diagnostictech.html
http://www.twinturbo.net/ttnetfaq/FA...agnostics.html
You have a 96 OBDII but the 90/95 codes on OBDI means the same.
OBDII Codes:
96 300ZX
P0100 MAF Sensor
P0110 IAT Sensor
P0115 ECT Sensor
P0120 TP Sensor
P0125 ECT Sensor
P0130 Front HO2S RH Bank
P0135 Front HO2S Heater RH Bank
P0136 Rear HO2S RH Bank
P0141 Rear HO2S Heater RH Bank
P0150 Front HO2S LH Bank
P0155 Front HO2S Heater LH Bank
P0156 Rear HO2S LH Bank
P0161 HO2S Heater LH Bank
P0171 Fuel Injection System Lean RH Bank
P0172 Fuel Injection System Rich RH Bank
P0174 Fuel Injection System Lean LH Bank
P0175 Fuel Injection System Rich LH Bank
P0180 Fuel Temperature Sensor
P0300 Multiple Cylinder Misfire
P0301–P0306 Misfire Cylinders 1–6
P0325 Knock Sensor
P0335 CKP Sensor
P0340 CMP Sensor
P0400 EGR Function
P0420 TWC Function
P0430 TWC Function
P0443 EVAP Canister Purge Control Solenoid Valve
P0500 VSS
P0505 IACV-AAC Valve
P0600 A/T Control & Communication Line
P0605 ECM-ECCS Control Module
P0705 PNP Switch
P1150 Wastegate Valve Control Solenoid Valve
P1155 Wastegate Valve Control Solenoid Valve
P1160 Turbocharger Boost Sensor
P1220 Fuel Pump Control Module
P1320 Ignition Signal
P0130 Front HO2S RH Bank
P0135 Front HO2S Heater RH Bank
P0136 Rear HO2S RH Bank
P0141 Rear HO2S Heater RH Bank
P0150 Front HO2S LH Bank
P0155 Front HO2S Heater LH Bank
P0156 Rear HO2S LH Bank
P0161 HO2S Heater LH Bank
P0171 Fuel Injection System Lean RH Bank
P0172 Fuel Injection System Rich RH Bank
P0174 Fuel Injection System Lean LH Bank
P0175 Fuel Injection System Rich LH Bank
P0180 Fuel Temperature Sensor
P0300 Multiple Cylinder Misfire
P0301–P0306 Misfire Cylinders 1–6
P0325 Knock Sensor
P0335 CKP Sensor
P0340 CMP Sensor
P0400 EGR Function
P0420 TWC Function
P0430 TWC Function
P0443 EVAP Canister Purge Control Solenoid Valve
P0500 VSS
P0505 IACV-AAC Valve
P0600 A/T Control & Communication Line
P0605 ECM-ECCS Control Module
P0705 PNP Switch
P1150 Wastegate Valve Control Solenoid Valve
P1155 Wastegate Valve Control Solenoid Valve
P1160 Turbocharger Boost Sensor
P1220 Fuel Pump Control Module
P1320 Ignition Signal