Circuit Description

WARNING: This page is about a different car, the 2000 Isuzu Hombre. However, it is still accessible from the selected car via links, so may be relevant.

A three-way catalytic converter is used to maintain low emissions. PCM monitors exhaust gasses from converter using Heated Oxygen Sensor (HO2S). HO2S is located in exhaust stream after the three-way catalytic converter. HO2S produces an output signal which indicates oxygen capacity of catalyst. This determines catalyst's ability to convert exhaust emissions effectively.

During normal operation, downstream HO2S signal will be less active than that produced by the front Oxygen Sensor (O2S). Powertrain Control Module (PCM) monitors catalyst efficiency in 2 stages. If catalyst efficiency falls to less than 75 percent, PCM will set a stage one fail flag, but will not illuminate Malfunction Indicator Light (MIL). If catalyst efficiency falls to less than 50 percent, PCM will set a stage 2 fail flag and MIL will be illuminated.

Conditions for setting this DTC are:

DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0131, P0132, P0133, P0134, P0137, P0138, P0140, P0141, P0171, P0172, P0200, P0300, P0301, P0302, P0303, P0304, P0502, P0506, P0507, P0562, P0563, P0601, P1133, P1171, P1336, P1404 and P1441 not set.
Engine speed running for greater than 510 seconds.
BARO greater than 72 kPa.
Fuel system in "closed-loop".
Engine operated at greater than 1200 RPM for longer than 60 seconds.
Battery voltage is greater than 9 volts. Or with vehicle stopped
Idling at less than 150 RPM from desired idle.
Transmission in Drive (A/T) or Neutral (M/T).
TP angle at zero percent.
ECT greater than 167°F (75°C).
IAT at greater than -4°F (-20°C) but less than 176°F (80°C).
Short term fuel trim is 93-163.
Catalytic temperature is greater than 653°F (345°C) on 2.2L engines.