Isuzu 1999 RODEO Workshop Manual page 1625

6E2–382
RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1134 HO2S Transition Time Ratio Bank 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 established. During the monitoring 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 P1134 will be set, indicating that the oxygen sensor
is not responding as expected to changes in exhaust
oxygen content.
Conditions for Setting the DTC
f No related DTCs.
f Engine coolant temperature (ECT) is above 50°C
(122°F) for automatic transmission; 75°C (167°F) for
manual transmission.
f Engine is operating in "closed loop."
f The engine has been running at least one minute.
f Canister purge duty cycle is greater than 2%.
f Engine speed is between 1500 RPM and 3000 RPM.
f Mass air flow (MAF) is between 9 g/second and 42
g/second.
Sensor 1
f Above conditions are present for a 3-second
monitoring period.
f 90 seconds after "closed loop" and stoichiometric
operation have been enabled, Bank 1 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
With this
f The PCM will illuminate the malfunction indicator lamp
(MIL) after second consecutive trip in which the fault is
detected.
f "Open loop" fuel control will be in effect.
f 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
f 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.
f A history DTC P1134 will clear after 40 consecutive
warm-up cycles have occurred without a fault.
f DTC P1134 can be cleared by using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
D06RW060