P1154 Ho2S Circuit Transition Time Ratio Bank 2 Sensor 1 - Isuzu 2000 Trooper Workshop Manual

P1154 HO2S Circuit Transition Time Ratio Bank 2 Sensor 1

Circuit Description
The powertrain control module (PCM) monitors the
heated oxygen sensor (HO2S) activity for 90 seconds
after "closed loop" and stoichiometric operation have
been enabled. During the monitor period the PCM counts
the number of times that the HO2S responds from
rich-to-lean and from lean-to-rich and adds the amount of
time it took to complete all transitions.
information, an average time for all transitions can be
determined. The PCM then divides the rich-to-lean
average by the lean-to-rich average to obtain a ratio. If
the HO2S transition time ratio is not within this range,
DTC P1154 will be set, indicating that the oxygen sensor
is not responding as expected to changes in exhaust
oxygen content.
Conditions for Setting the DTC
D No related DTCs.
D Engine coolant temperature (ETC) is above 50°C
(122°F) for automatic transmission; 75°C (167°F) for
manual transmission.
D The engine is operating in "closed loop."
D The engine has been running at least one minute.
D Canister purge duty cycle is greater than 2%.
D Engine speed is between 1500 RPM and 3000 RPM.
D Mass air flow is between 9 g/second and 42 g/second.
D Above conditions are present for a 3-second
monitoring period.
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
With this
D 90 seconds after "closed loop" and stoichiometric
operation have been enabled, Bank 2 HO2S 1
transition ratio between lean to rich and rich to lean is
less than 0.44 or greater than 3.8.
Action Taken When the DTC Sets
D The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
D "Open loop" fuel control will be in effect.
D The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
D A history DTC P1154 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P1154 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
Diagnostic Aids
A multifunction in the HO2S heater ignition feed or ground
circuit may cause a DTC P1154 to set. Check HO2S
heater circuitry for intermittent faults or poor connections.
If connections and wiring are OK and DTC P1154
continues to set, replace the Bank 2 HO2S 1.
6E–405
D06RY00175