The 5-1-1 code is from the mass airflow sensor:

5-1-1 (Adaptive HO2S Control Provides Leaner Mixture At Idle)

1) Turn ignition on. Connect voltmeter between Mass Airflow
(MAF) sensor connector terminal No. 4 and ground. See Fig. 5. If
voltmeter indicates about 2.7 volts, go to next step. If voltage is
not to specification, clean MAF sensor connector and repeat test. If
still incorrect, repeat test using new MAF sensor.

2) Check engine oil level and condition and adjust as
necessary. If oil level was incorrect or oil was contaminated, clear
codes. If oil level and oil condition are okay, check Fuel Evaporative
(EVAP) system and repair as necessary. See I - SYSTEM/COMPONENT TESTS
article. If EVAP system is okay, check fuel pressure. See FUEL SYSTEM
in the C - SPECIFICATIONS article. If fuel pressure is incorrect,
repair as necessary and clear codes.

3) If fuel pressure is correct, check fuel injection ECU
signals. See ELECTRONIC CONTROL UNIT - FUEL INJECTION in the
I - SYSTEM/COMPONENT TESTS article. Clear codes.


The 1-1-3 code is from the mass airflow sensor or a vacuum leak or the Oxygen sensor screwed up or .... here's what the book says, I'll try to email you the whole .pdf file because its pretty long winded.

Code 1-1-3 or 2-2-1 means that engine is running lean.
This may be caused by an air leak or an HO2S sensor fault. Code 2-3-1
or 5-1-2 means that engine is running rich. This may be caused by high
fuel pressure, leaking injector(s), faulty MAF signal or faulty HO2S
sensor.

2) Connect measuring unit to fuel injection ECU. See
MEASURING UNIT under SELF-DIAGNOSTIC SYSTEM. To check HO2S sensor
signal, start engine. Connect voltmeter between measuring unit
terminals No. 22 and 23. Voltage should vary between .1-.9 volt after
about 30 seconds.

3) If voltmeter indicates a constant one or zero volts, HO2S
sensor is interpreting lean air/fuel ratio or is shorted to ground.
Disconnect HO2S sensor connector at firewall. Use a voltmeter and
backprobe between connector terminal No. 2 and ground. See Fig. 4.

4) If voltage remains constant at zero or one volt, check
engine CO adjustment. If voltage varies between .1-.9 volt and code is
still present, HO2S control is adjusting CO correctly but fuel
injection ECU is indicating fault. Check engine CO.

5) To check CO, connect CO meter to CO tap in exhaust pipe.
Start and run engine to operating temperature. Disconnect HO2S
connector. Display, record, then erase codes. Check CO.

6) If meter indicates low CO and engine operates very
unevenly, engine is running lean. See Codes 1-1-3 and 2-2-1. If meter
indicates high CO (greater than 2.5 percent), engine is running rich
and system must make mixture leaner to compensate for fuel leakage or
other fault. See Codes 2-3-1 and 5-1-2.

7) If CO content is .3-2.5 percent and engine runs normally,
reconnect HO2S sensor and recheck CO content. If reading becomes too
high or low, repeat test using new HO2S sensor. If CO content is still
incorrect, repeat test using new fuel injection ECU.


Mike