P0405

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
A EGR Control Pressure/Baro sensor is used to monitor the amount of vacuum in the EGR circuit, It senses the actual vacuum in the EGR vacuum line and sends a signal back to the Powertrain Control Module (PCM). This signal is used to control EGR duty cycle calculated by the PCM. This is a type B DTC.

CONDITIONS FOR SETTING THE DTC
- Actual EGR less than or equal to 0.24 volts (15 kPa).
- Condition met for 2 seconds.

ACTION TAKEN WHEN THE DTC SETS
The PCM will shut down the EGR.

CONDITIONS FOR CLEARING THE MIL/DTC
- The PCM will turn the MIL off after three consecutive trips without a fault condition.
- A History DTC will clear when forty consecutive warm-up cycles that the diagnostic does not fail (coolant temperature has risen 5°C (40°F) from start up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle.

DIAGNOSTIC AIDS
With the ignition ON and the engine stopped the EGR pressure is equal to atmospheric pressure with the signal voltage being high. The information is used by the PCM as an indication of vehicle altitude. Comparison of this reading with a known good vehicle with the same sensor is a good way to check accuracy of a suspect' sensor. Readings should be the same + 0.4 volt. An intermittent open in signal circuit or the 5 volt reference circuit will result in a DTC P0405.

TEST DESCRIPTION
Number(s) below refer to the Step number(s) on the Diagnostic Table.

2. This Step determines if P0405 is a hard failure or an intermittent condition.
3. Jumpering the 5 volt reference circuit to the signal circuit will determine if the sensor is at fault, or if there is a problem with the PCM or wiring.
4. The scan tool may not display 5 volts. The important thing is that the PCM recognized the voltage as more than 4 volts, indicating that the PCM and the signal circuit are OK.