Diagnostic Trouble Code (Dtc) P0401 Exhaust Gas Recirculation (Egr) Flow Insufficient Detected - Isuzu 1999 RODEO Workshop Manual

6E1–232 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0401 EXHAUST GAS RECIRCULATION
Circuit Description
The powertrain control module (PCM) tests the exhaust
gas recirculation (EGR) system during deceleration by
momentarily commanding the EGR valve to open while
monitoring the manifold absolute pressure (MAP) sensor
signal. When the EGR valve is opened, the PCM monitors
the change in MAP input signal. The PCM compares the
MAP change to a RPM vs. BARO table. When the PCM
interprets the change in MAP to be out of limits, the PCM
will set DTC P0401. The number of test samples required
to accomplish this may vary according to the severity of
the detected flow error.
Normally, the PCM will only allow one EGR flow test
sample to be taken during an ignition cycle. To aid in
verifying a repair, the PCM allows twelve test samples
during the first ignition cycle following a Tech 2 "Clear Info"
or a battery disconnect. Between nine and twelve
samples should be sufficient for the PCM to determine
adequate EGR flow and pass the EGR test. DTC P0401
is a type A code.
Conditions for Setting the DTC
f No TP sensor, VSS, EVAP Purge, IAC, IAT sensor,
MAP sensor, EGR Pintle Position sensor, ECT sensor,
misfire DTCs set.
f Barometric pressure is above 72 kPa.
(EGR) FLOW INSUFFICIENT DETECTED
f Engine coolant temperature is greater than 60°C
(140°F).
f System voltage is between 11.5 and 16 volts.
f Vehicle speed is greater than 23 km/h (14 mph).
f IAC position is steady, changing less than 5 counts.
f A/C clutch status is unchanged.
Start Test
f TP angle is less than 0.8%.
f EGR duty cycle is less than 1%.
f MAP is steady, changing less than 1 kPa.
f Engine speed is between 1200 RPM and 2000 RPM.
f Compensated MAP between 10.3 kPa and 49.8 kPa.
Run Test
f Delta MAP is recorded during valve open conditions.
f EGR valve is ramped over a time interval.
Run Test will be aborted if any of the following are true:
f Vehicle speed changes by greater than 16 km/h
(10mph).
f Engine RPM changes by greater than 100 rpm.
f EGR is opened less than 95% of the commanded
amount.
During the Start Test and the Run Test, the EGR is closed
then opened. The associated change in MAP is
compared with the PCM's expected change value. If the
D06RX055