This might be helpful to some people and might also be good in the FAQ section.
11 ECU(+B)
Diagnosis
* Momentary interruption in power supply to ECU.
Trouble Area
* Ignition switch circuit
* Ignition switch
* Main relay circuit
* Main relay
* ECU
12 RPM Signal
Diagnosis
* No "NE" or "G" signal to ECU within 2 seconds after engine has been cranked.
Trouble Area
* Distributor, or CPS, circuit
* Distributor or CPS
* Starter signal circuit
* ECU
13 RPM Signal
Diagnosis
* No "NE" signal to ECU when engine speed is about 1,000 RPM.
Trouble Area
* Distributor, or CPS, circuit
* Distributor or CPS
* ECU
14 Ignition Signal
Diagnosis
* No "IGF" signal to ECU "A" times in succession.
A = 6-8 (7M-GE)
A= 3 (7M-GTE)
Trouble Area
* Igniter and ignition coil circuit
* Igniter and ignition coil
* ECU
21 Oxygen Sensor Signal
Diagnosis
* Detection of oxygen sensor deterioration.
Trouble Area
* Oxygen sensor circuit
* Oxygen sensor
* ECU
22 Water Temp Sensor Signal
Diagnosis
* Open or short circuit in water temp sensor signal (THW).
Trouble Area
* Water temp sensor circuit
* Water temp sensor
* ECU
24 Intake air Temp Sensor Signal
Diagnosis
* Open or short circuit in intake air temp sensor signal (THA).
Trouble Area
* Intake air temp sensor circuit
* Intake air temp sensor
* ECU
25 Air-Fuel Ratio Lean Malfunction
Diagnosis
* When air-fuel ratio feedback compensation value or adaptive control value continues at the upper(lean) or lower(rich) limit renewed for a certain period of time.
* When air-fuel ration feedback compensation value or adaptive control value feedback frequency is abnormally high during feedback condition.
* When marked variation is detected in engine revolutions for each cylinder during idle switch on and feedback condition.
Trouble Area
* Injector circuit
* Injector
* Fuel line pressure
* Air flow meter
* Air intake system
* Oxygen sensor circuit
* Oxygen sensor
* Ignition system
* Water temp sensor
* ECU
26 Air-Fuel Ratio Rich Malfunction
Diagnosis
* When air-fuel ratio feedback compensation value or adaptive control value continues at the upper(lean) or lower(rich) limit renewed for a certain period of time.
* When air-fuel ration feedback compensation value or adaptive control value feedback frequency is abnormally high during feedback condition.
* When marked variation is detected in engine revolutions for each cylinder during idle switch on and feedback condition.
Trouble Area
* Injector circuit
* Injector
* Fuel line pressure
* Air flow meter
* Cold start injector
* Oxygen sensor circuit
* Oxygen sensor
* Water temp sensor
* ECU
27 Sub-Oxygen Sensor Signal or Sensor Heater
Diagnosis(Sub-Oxygen Sensor Signal)
* Open or short circuit in sub-oxygen sensor signal (OX2).
Trouble Area
* Sub-oxygen sensor circuit
* Sub-oxygen sensor
* ECU
Diagnosis(Sub-Oxygen Sensor Heater)
* Open or short circuit in sub-oxygen sensor heater (HT).
Trouble Area
* Sub-oxygen sensor heater circuit
* Sub-oxygen sensor heater
* ECU
31 Air Flow Meter Signal
Diagnosis
* (7M-GE) Open circuit in VC signal or short circuit between VS and E2 when idle contacts are closed.
* (7M-GTE) Open or short circuit in air flow meter signal.
Trouble Area
* Air flow meter circuit
* Air flow meter
* ECU
32
Air Flow Meter Signal(7M-GE)
HAC Sensor Signal(7M-GTE)
Diagnosis(Air Flow Meter Signal(7M-GE))
* Open circuit in E2 or short circuit between VC and VS.
Trouble Area
* Air flow meter circuit
* Air flow meter
* ECU
Diagnosis(HAC Sensor Signal(7M-GTE))
* Open circuit or short circuit in HAC sensor signal.
Trouble Area
* ECU
34 Turbocharger Pressure
Diagnosis
* The turbocharger pressure is abnormal.
Trouble Area
* Turbocharger
* Air flow meter
* ECU
* Intercooler system
41 Throttle Position Sensor Signal
Diagnosis
* Open or short circuit in throttle position sensor signal.
Trouble Area
* Throttle position sensor circuit
* Throttle position sensor
* ECU
42 Vehicle Speed Sensor Signal
Diagnosis
* No "SPD" signal to ECU for 8 seconds when engine speed is between 2,500RPM and 4,500RPM (7M-GE) or 4,000RPM (7M-GTE) and coolant temp is below 80°C(176°F) and neutral start switch is off.
Trouble Area
* Vehicle speed sensor circuit
* Vehicle speed sensor
* ECU
43 Starter Signal
Diagnosis
* No "STA" signal to ECU until engine speed reaches 800RPM with vehicle not moving.
Trouble Area
* Ignition switch circuit.
* Ignition switch
* ECU
51 Switch Signal
Diagnosis
* No "IDL" signal, "NSW" signal or "A/C" signal to ECU, during diagnosis check.
Trouble Area
* A/C switch circuit
* A/C switch
* A/C amplifier
* Throttle position sensor circuit
* Throttle position sensor
* ECU
52 Knock Sensor Signal
Diagnosis
* Open or short circuit in knock sensor signal.
Trouble Area
* Knock sensor circuit
* Knock sensor
* ECU
53 Knock Control Signal in ECU
Diagnosis
* Knock control program faulty.
Trouble Area
* ECU
71 EGR System Malfunction
Diagnosis
* EGR gas temp below predetermined level during EGR operation.
* Open circuit in EGR gas temp sensor signal (THG).
Trouble Area
* EGR system (EGR valve, EGR hose etc.)
* EGR gas temp sensor circuit
* EGR gas temp sensor
* VSV for EGR circuit
* VSV for EGR
* ECU