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 should see a proportional increase in MAP. If the expected increase in MAP is not seen, the PCM notes the amount of error that was detected and adjusts an internal fail counter towards a fail threshold level. When the fail counter exceeds the fail threshold level, the PCM will set this DTC. The number of test samples required to accomplish this may vary according to the amount of detected flow error.
Normally, the PCM will only allow 1 EGR flow test sample to be taken during an ignition cycle. In order to aid in verifying a repair, the PCM allows 12 test samples during the first ignition cycle following a scan tool Clear Info or a battery disconnect. Between 9-12 samples should be sufficient for the PCM to determine adequate EGR flow and pass the EGR test.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0201-P0206, P0300, P0336, P0403, P0404, P0405, P0502, P0503, P0506, P0507, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122, P1374, or P1404 are not set. |
| • | The system voltage is between 10-18 volts. |
| • | The AC status does not change. |
| • | The transaxle range does not change. |
| • | The throttle position (TP) angle is less than 1 percent, deceleration. |
| • | The intake air temperature (IAT) is more than 80°C (176°F). |
| • | The engine coolant temperature (ECT) is more than 75°C (167°F). |
| • | The engine speed is between 1,050-1,300 RPM. |
| • | The idle air control (IAC) position is steady. |
| • | The MAP is steady between 15-70 kPa. |
| • | The vehicle speed is more than 56 km/h (35 mph) during deceleration. |
| • | The barometric pressure (BARO) sensor less than 70 kPa. |
| • | The vehicle will need to be driven above 80 km/h (50 mph), and then allowed to decelerate. When the vehicle is decelerating while meeting all of the criteria listed above, the PCM will enable the test to run. When the test is running, you will see the desired EGR parameter and the EGR position sensor on the scan tool change from 0 to a calibrated value above 0. |
Conditions for Setting the DTC
The MAP changes monitored during EGR flow test indicate insufficient EGR flow.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
IMPORTANT: Inspect for the following conditions:
• Vacuum restriction to the MAP sensor--A restriction to the MAP
sensor can cause the EGR flow test to fail due to insufficient MAP changes
being monitored during the test. Inspect for objects blocking the vacuum
to the MAP sensor. • An engine that is running poorly may cause this DTC to set. • Poor connection or damaged harness--Inspect the wiring harness
for damage. • If the harness appears to be OK, observe the EGR position sensor display
on the scan tool while moving the connectors and the wiring harnesses
that are related to the EGR valve. A change in the display indicates the
location of the malfunction.
In order to verify a repair, clear info with the scan tool and run the EGR flow test, keeping the following conditions in mind:
| • | The PCM will only run the EGR flow test during a gradual deceleration. |
| • | The PCM will only run the EGR test during a closed throttle condition. |
| • | The PCM will only run the EGR test at vehicle speeds above 56 km/h (35 mph). |
| • | Several deceleration cycles, typically 9-12, will be necessary in order to run a sufficient number of EGR flow test samples. |
| • | The EGR Test Counter displayed on the scan tool can be useful in determining that the EGR flow test is running, and to track the number of test samples taken. The counter will increment each time a test sample is taken. |
Test Description
The number below refers to the step number on the diagnostic table.
-
This DTC is set when the PCM does not detect a predetermined change in MAP when the EGR valve is commanded. This step inspects for any MAP sensor DTCs. A malfunctioning MAP sensor may cause this DTC to set.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | Go to Step 2 | |||||
Are there any manifold absolute pressure (MAP) DTCs set? | Go to Step 3 | ||||||
3 |
Did you find and correct the condition? | Go to Step 7 | Go to Step 4 | ||||
4 |
Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | ||||
5 |
Did you find and correct the condition? | Go to Step 7 | Go to Step 6 | ||||
6 |
Did you find and correct the condition? | Go to Step 7 | Go to Diagnostic Aids | ||||
7 |
Does the DTC run and pass? | Go to Step 8 | Go to Step 2 | ||||
8 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |||||
