Diagnostic Trouble Code (Dtc) P0404 Exhaust Gas Recirculation (Egr) Circuit Range/Performance - Isuzu 1999 RODEO Workshop Manual

DIAGNOSTIC TROUBLE CODE (DTC) P0404 EXHAUST GAS RECIRCULATION
Circuit Description
An Exhaust Gas Recirculation (EGR) system is used to
lower Oxides of Nitrogen (NOx) emission levels caused
by high combustion temperatures. It accomplishes this
by feeding small amounts of exhaust gases back into the
combustion chamber. When the air/fuel mixture is diluted
with the exhaust gases, combustion temperatures are
reduced.
A linear EGR valve is used on this system. The linear
EGR valve is designed to accurately supply exhaust
gases to the engine without the use of intake manifold
vacuum. The valve controls exhaust flow going into the
intake manifold from the exhaust manifold through an
orifice with a PCM controlled pintle. The PCM controls
the pintle position using inputs from the Throttle Position
(TP) and Manifold Absolute Pressure (MAP) sensors.
The PCM then commands the EGR valve to operate
when necessary by controlling an ignition signal through
the PCM. This can be monitored on a Tech 2 as the
Desired EGR Position.
The PCM monitors the results of its command through a
feedback signal. By sending a 5 volt reference and a
ground to the EGR valve, a voltage signal representing
the EGR valve pintle position is sent to the PCM. This
feedback signal can also be monitored on a Tech 2 and is
the actual position of the EGR pintle. The Actual EGR
position should always be near the commanded or
Desired EGR Position.
RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
(EGR) CIRCUIT RANGE/PERFORMANCE
If the PCM detects a large difference between the
desired EGR position and actual EGR position, then
Diagnostic Trouble Code P0404 will set. DTC P0404 is a
type B code.
Conditions for Setting the DTC
f IAT is greater than 5°C (41°F).
f EGR commanded ON (Desired EGR Position is
greater than 0%).
f Actual EGR Position differs from Desired EGR
Position by more than 15% for 5 seconds.
Action Taken When the DTC Sets
f Malfunction Indicator Lamp (MIL) will illuminate the
second time the fault is detected.
f The PCM will record operating conditions at the time
the diagnostic fails.
f A history Diagnostic Trouble Code is stored.
f The EGR Valve is disabled.
Conditions for Clearing the MIL/DTC
f The MIL will turn OFF after three consecutive ignition
cycles in which the diagnostic runs without a fault.
f Diagnostic Trouble Code(s) can be cleared by using a
Tech 2.
6E1–237
D06RX055