Diagnostic Trouble Code (Dtc) P0172 System Too Rich (Bank 1) - Isuzu 1999 RODEO Workshop Manual

DIAGNOSTIC TROUBLE CODE (DTC) P0172 SYSTEM TOO RICH (BANK 1)

Circuit Description
To provide the best possible combination of driveability,
fuel economy, and emission control, a "Closed Loop"
air/fuel metering system is used. While in "Closed Loop",
the powertrain control module (PCM) monitors the Bank 1
heated oxygen sensor (HO2S) 1 and adjusts fuel delivery
based upon the HO2S signal voltages. A change made to
fuel delivery will be indicated by the long and short term
fuel trim values which can be monitored with a Tech 2.
Ideal fuel trim values are around 0%; if the HO2S signals
are indicating a lean condition the PCM will add fuel,
resulting in fuel trim values above 0%. If a rich condition is
detected, the fuel trim values will be below 0%, indicating
that the PCM is reducing the amount of fuel delivered. If
an excessively rich condition is detected on Bank 1, the
PCM will set Diagnostic Trouble Code P0172. DTC
P0172 is a type B code.
The PCM's maximum authority to control long term fuel
trim allows a range between –14% and +20%. The PCM's
maximum authority to control short term fuel trim allows a
range between –11% and +20%. The PCM monitors fuel
trim under various engine speed/load fuel trim cells
before determining the status of the fuel trim diagnostic.
Conditions for Setting the DTC
f No Tech 2 test is being run.
f None of the following was set: EGR Diagnostic Trouble
Codes, HO2S Diagnostic Trouble Codes, (response,
transition, open, low volts, no activity), TPS Diagnostic
Trouble Codes, MAP Diagnostic Trouble Codes, IAT
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
Diagnostic Trouble Codes, canister purge Diagnostic
Trouble Codes, EVAP Diagnostic Trouble Codes,
injector circuit Diagnostic Trouble Codes, or misfire
Diagnostic Trouble Codes.
f Engine coolant temperature is between 65°C (149°F)
and 104°C (219°F).
f Intake air temperature is between –40°C (–40°F) and
120°C(248°F).
f Manifold absolute pressure is between 23.75 kPa and
99 kPa.
f System voltage is greater than 9.5 volts.
f Engine speed is between 400 and 6000 RPM.
f Barometric pressure is greater than 72.3 kPa.
f Engine is operating in "Closed Loop".
f The average of the long term full trim samples is less
than 1.03 and the average of the adaptive index
multiplier samples is less than or equal to 0.82.
Action Taken When the DTC Sets
f The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
f The PCM will store conditions which were present
when the Diagnostic Trouble Code 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.
6E1–175
D06RX048