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Dan, Technician
Category: GMC
Satisfied Customers: 24584
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Databases
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405 trouble code on a 2003 gmc duramx, 405, and yes I've

Customer Question

405 trouble code on a 2003 gmc duramx
JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: 405, and yes I've reset it
JA: What is the model of your '03 GMC?
Customer: gmc 2003 sierra 2500 hd
JA: Are you fixing your Sierra yourself? What have you tried so far?
Customer: It says it's low voltage, so I've looked at wiring harnesses
JA: Anything else you want the mechanic to know before I connect you?
Customer: I have recently changed the fuel filter housing, and that's when the code started
Submitted: 2 months ago.
Category: GMC
Expert:  Dan replied 2 months ago.

Hello, my name is ***** ***** I'm here to help get your problem solved.

Customer: replied 2 months ago.
Where is the low voltage sensor located?
Expert:  Dan replied 2 months ago.

This usually means the EGR valve vacuum control solenoid has failed or vacuum line going to solenoid is leaking. Verify ignition feed to the three EGR solenoids, Pink wire. Test vacuum from the vacuum pump to the EGR valve vacuum control solenoid. Should have 19-20" vacuum with engine running. Check the EGR Valve Vacuum Control Solenoid for a ground pulse on the White wire from the ECM while the engine is running and EGR is commanded. The EGR valve vacuum control solenoid is normally closed. Check the EGR Vacuum Vent Solenoid control wire, White wire. This wire should be grounded by the ECM to block a vent path when the EGR is commanded ON. Here is also information from manual for code, let me know if you have questions. Thanks.


Expert:  Dan replied 1 month ago.

Ever get it figured out? Please do not forget to rate answer, I am not compensated for time/information until you leave rating. Thanks.