P1133 Ho2S Insufficient Switching Bank 1 Sensor 1 - Isuzu 2000 Trooper Workshop Manual

P1133 HO2S Insufficient Switching Bank 1 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 this test period the PCM counts the
number of times that the HO2S signal voltage crosses the
rich-to-lean and lean-to-rich threshold.
determines that the HO2S did not switch enough times,
DTC P1133 will be set.
A lean-to-rich switch is determined when the HO2S
voltage changes above and below 450 mV.
Heated oxygen sensors are used to minimize the amount
of time required for "closed loop" fuel control operation
and to allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank
2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature for accurate exhaust oxygen
content readings further from the engine.
Conditions for Setting the DTC
D Engine coolant temperature (ECT) is above 50°C
(122°F) for automatic transmission; 75°C (167°F) for
manual transmission.
D Engine is operating in "closed loop".
D The engine has been running at least one minute.
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC)
If the PCM
D Canister purge duty cycle is greater than 2%.
D Engine speed is between 1500 RPM and 3000 RPM.
D Mass air flow (MAF) is between 9 g/second and 42
g/second.
D Above conditions are present for 3 seconds.
D 90 seconds after "closed loop" and stoichiometric
operation have been achieved, the PCM monitors the
oxygen sensor as it switches above and below 450 mV.
If fewer than 23 rich-to-lean and lean-to-rich switches
are detected, DTC P1133 will be set.
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 P1133 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
D DTC P1133 can be cleared by using Tech 2 "Clear Info"
function or by disconnecting the PCM battery feed.
6E–393
D06RY00171