Circuit Description
The engine control module (ECM) performs a flow test on the exhaust gas recirculation (EGR) system during deceleration. The ECM does this by momentarily commanding the EGR valve to open while monitoring the signal of the manifold absolute pressure (MAP) sensor and the EGR position sensor. If the MAP signal is incorrect for the EGR pintle position, the ECM records the amount of MAP difference that was detected and adjusts a calibrated fail counter towards a calibrated fail threshold level. The number of EGR flow tests required to exceed the fail threshold may vary according to the amount of detected EGR flow error. If the ECM detects an EGR flow error, this DTC sets.
Normally, the ECM will only allow one EGR flow test during an ignition cycle. To aid in verifying a repair, the ECM will allow multiple EGR flow tests following a code clear event.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1402 Exhaust Gas Recirculation (EGR) Flow Insufficient
Conditions for Running the DTC
| • | DTCs P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0131, P0300, P0335, P0336, P0337, P0341, P0342, P1320, and P1321 are not set. |
| • | The engine is operating in closed loop. |
| • | Engine coolant temperature (ECT) is greater than 80°C (176°F). |
| • | Intake air temperature (IAT) is greater than 15°C (59°F). |
| • | Manifold absolute pressure is greater than 75 kPa (10.9 psi). |
| • | The EEGR differential rate is less than 3 percent. |
| • | Engine speed is between 2,500-2,900 RPM. |
| • | DTC P1402 runs once an ignition cycle once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects the incorrect amount of intake absolute pressure when compared to the EGR valve position during the EGR flow test.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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MAP sensor faults must be diagnosed first. A skewed MAP sensor reading could cause this DTC to set.
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An engine mechanical condition may cause the engine to operate poorly, which could cause a low vacuum condition.
Step | Action | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | |||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |||||||||
2 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Intermittent Conditions | ||||||||
Is DTC P0107 or P0108 also set? | Go to Step 4 | ||||||||||
4 | Inspect the exhaust gas recirculation (EGR) system for the following conditions:
Did you find and correct the condition? | Go to Step 9 | Go to Step 5 | ||||||||
5 | Inspect for leaks or restrictions at the manifold absolute pressure (MAP) sensor. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 | ||||||||
6 | Inspect the exhaust system for the following conditions:
Did you find and correct the condition? | Go to Step 9 | Go to Step 7 | ||||||||
Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | |||||||||
8 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | Go to Step 9 | -- | ||||||||
9 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 10 | ||||||||
10 | Are there any DTCs that have not been diagnosed? | System OK | |||||||||
