Circuit Description
The powertrain control module (PCM) tests the 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 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 scan tool 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.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0336, P0403, P0404, P0502, P0503, P0506, P0507, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122, P1374, 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. |
| • | Intake air temperature is greater than 80°C (176°F). |
| • | Engine coolant temperature is greater than 75°C (167°F). |
| • | Engine speed is between 1,050-1,300 RPM. |
| • | IAC position is steady. |
| • | MAP is steady between 15-70 kPa. |
| • | Vehicle speed is greater than 35 mph during deceleration. |
| • | BARO sensor more than 70 kPa. |
| • | The vehicle will need to be driven above 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. As 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
MAP changes monitored during EGR flow test indicate insufficient EGR flow.
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the first trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using 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 connectors and wiring harnesses related
to the EGR valve. A change in the display indicates the location of the
malfunction.
To verify a repair, clear info with the scan tool and run the EGR flow test keeping the following items 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 35 mph. |
| • | Several deceleration cycles will be necessary to run a sufficient number of EGR flow test samples, 9-12. |
| • | The EGR Test Counter displayed on the scan tool can be useful in determining that the EGR flow test is running and to keep track of the number of test samples taken. The counter will increment each time a test sample is taken. |
Test Description
The numbers below refer to the step numbers 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 checks for any MAP sensor DTCs. A malfunctioning MAP sensor may cause this DTC to set.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||
Is there any MAP DTCs set? | -- | Go to the applicable DTC | 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 in Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||
