p0405B

[c10 custom]

hi guys i have a 1999 chev new body style chev truck and i have trouble code p0405B exhaust gas recirculation position sensor circuit low voltage what could cause this any help greatly appreciated

[clinebarger]

1. Check the EGR position sensor voltage with a Digital Volt Ohm Meter (DVOM), Brown wire.

2. Compare this voltage to scan data value for the EGR position.

3. If the voltage on the Brown wire drops low at any time, then check the 5 V reference to the EGR valve, Gray wire.

4. If the voltage on the Gray wire drops low at any time, check again with the Fuel Tank Pressure (FTP) sensor disconnected. Ive seen faulty FTP sensors cause this code.


Possible Causes Setting Conditions for P0405
•EGR position sensor signal circuit is open
•EGR position sensor signal circuit is shorted to ground
•EGR position sensor reference (5v) circuit is open or shorted to ground
•EGR position sensor has failed
•PCM has failed
Or the FTP sensor thats NOT in any literature ive read.

DTC P0405 EXHAUST GAS RECIRCULATION (EGR) POSITION SENSOR CIRCUIT LOW VOLTAGE (ENGINE CONTROLS - 4.8L, 5.3L, AND 6.0L)

Circuit Description
An Exhaust Gas Recirculation (EGR) system is used in order to lower Oxides of Nitrogen (NOx) emission levels. The EGR system accomplishes this by recirculating small amounts of exhaust gas back into the combustion chamber. High combustion temperatures cause NOx. Combustion temperatures are reduced when the air/fuel mixture is diluted with the exhaust gases.

The EGR valve is designed to accurately supply exhaust gases to the engine without the use of intake manifold vacuum. The EGR valve controls the exhaust flow into the intake manifold from the exhaust manifold through an orifice with a PCM controlled pintle. The PCM controls the pintle position using inputs from the Throttle Position (TP) sensor, the Manifold Absolute Pressure (MAP) sensor and, the Engine Coolant Temperature (ECT) sensor. The PCM commands the EGR valve in order to supply the correct amount of exhaust gas recirculation for the current engine operating conditions. This can be monitored on a scan tool as the Desired EGR Position.

The PCM monitors the position of the EGR valve through a feedback signal. The PCM supplies a 5.0 volt reference circuit and a ground circuit to the EGR valve. A voltage signal representing the EGR valve pintle position is sent to the PCM from the EGR valve. This feedback signal can also be monitored on a scan tool and is the actual position of the EGR pintle. The Actual EGR Position should be near the Desired EGR Position.