DTC P0405 Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage. Pontiac Bonneville 1998

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1998 🢒 Bonneville 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P0405 Exhaust Gas Recirculation (EGR) Position Sensor Circuit Low Voltage

Engine Controls Components
Cell 20: Engine Controls - PCM EVAP and EGR Control
OBD II Symbol Description Notice

Circuit Description

The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor circuit is open or shorted. If the PCM detects an excessively low EGR Feedback signal voltage, DTC P0405 will set.

Conditions for Running the DTC

•	No TP, MAF, HO2S, IAT, or ECT DTCs are set.

•	Engine run time met. The time ranges from 45 seconds to 8.5 minutes depending upon engine coolant temperature at startup.

•	TP angle is greater than 2 percent.

•	System voltage is greater than 10 volts.

Conditions for Setting the DTC

•	EGR Feedback is less than 0.14 volt at any time.

•	The condition is present for longer than 20 seconds.

Action Taken When the DTC Sets

•	The PCM will illuminate the MIL during the second consecutive trip in which the diagnostic test has been run and failed.

•	The PCM will disable EGR for the rest of the ignition cycle.

•	The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data.

Conditions for Clearing the MIL/DTC

•	The PCM will turn the MIL OFF 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 the scan tool Clear Info function or by disconnecting the PCM battery feed.

Diagnostic Aids

•	Poor connection at PCM or EGR Valve.

Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

•	Damaged harness.

Inspect the wiring harness for damage. If the harness appears to be OK, connect DMM and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the DMM display will indicate the location of the malfunction.

Test Description

Numbers below refer to the step numbers on the Diagnostic Table:

Verifies that the malfunction is present.

If DTC P0405 will only set under certain conditions, the malfunction may be intermittent; refer to Diagnostic Aids. If an intermittent wiring problem is not present, check for a poor connection at the PCM or the EGR valve.

This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

DTC P0405 - EGR Valve Pintle Position Circuit Low Voltage

Step

Action

Values

Yes

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Turn ON the ignition switch.
Select the scan tool EGR valve output control function.
Increment the EGR valve through all positions while comparing Desired EGR Position to Actual EGR Position.

Does Desired EGR Position remain close to Actual EGR Position at all commanded positions?

Go to Step 3

Go to Step 4

Review and record scan tool Fail Records data.
Operate the vehicle within Fail Records conditions.
Using a scan tool, monitor Specific DTC info for DTC P0405.

Does the scan tool indicate DTC P0405 failed this ign?

Go to Step 4

Go to Diagnostic Aids

Disconnect the EGR valve electrical connector.
Connect a digital multimeter to measure voltage between the EGR pintle position sensor ground circuit and the 5 volt reference A circuit at the EGR valve connector.

Is the voltage at the specified value?

Go to Step 5

Go to Step 9

Probe the EGR valve pintle position circuit at the EGR valve harness connector with a test lamp connected to B+.

Is the test lamp ON?

Go to Step 8

Go to Step 6

Connect a jumper between the 5 volt reference A circuit and the pintle position circuit at the EGR valve connector.
Observe Actual EGR Position on the scan tool.

Is Actual EGR Position at the specified value?

100%

Go to Step 13

Go to Step 7

Turn OFF the ignition switch.
Disconnect the PCM.
Check for an open in the EGR pintle position circuit.
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

Go to Step 19

Go to Step 17

Turn OFF the ignition switch.
Disconnect the PCM.
Probe the EGR valve pintle position circuit with a test lamp to B+.

Is the test lamp ON?

Go to Step 12

Go to Step 15

Probe the 5 volt reference A circuit with a test lamp to B+.

Is the test lamp ON?

Go to Step 10

Go to Step 11

Turn OFF the ignition switch.
Disconnect the PCM.
Probe the 5 volt reference A circuit with a test lamp to B+.

Is the test lamp ON?

Go to Step 16

Go to Step 18

Check for an open in the 5 volt reference A circuit between the PCM and the EGR valve.
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

Go to Step 19

Go to Step 17

Locate and correct the short to ground in the EGR valve pintle position circuit. Refer to Wiring Repairs in Wiring Systems.

Is action complete?

Go to Step 19

Check for the following conditions:

•	Poor terminal connections at the EGR valve.

•	The EGR pintle position signal circuit shorted to the EGR valve control circuit.

If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

Go to Step 19

Go to Step 14

Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement .

Notice: If the EGR valve shows signs of excessive heat, inspect the exhaust system for blockage--possibly a plugged converter--using the procedure found on the Restricted Exhaust System Check. If the exhaust system is restricted, repair the cause. Inspect for an open injector caused by one or more of the following conditions:

•

Stuck

•	Grounded driver circuit

•	Possible faulty control module

If one of the above conditions is found, inspect the oil for possible fuel contamination.

Is action complete?

Go to Step 19

Check the EGR valve pintle position circuit for a short to the sensor ground circuit.
If a problem is found, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a problem found?

Go to Step 19

Go to Step 18

Locate and repair short to ground in the 5 volt reference A circuit. Refer to Wiring Repairs in Wiring Systems.

Is action complete?

Go to Step 19

Check the circuits related to the EGR valve for a poor terminal connection at the PCM.
If a problem is found, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Was a problem found?

Go to Step 19

Go to Step 18

Important:: The replacement PCM must be programmed.

Replace the PCM.

Refer to Powertrain Control Module Replacement/Programming .

Is action complete?

Go to Step 19

Review and record scan tool Fail Records data.
Clear DTCs.
Operate the vehicle within Fail Records conditions.
Using a scan tool, monitor Specific DTC info for DTC P0405.

Does the scan tool indicate DTC P0405 failed this ignition?

Go to Step 2

System OK