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1999 Chevy Suburban P0405 and P0404 Codes: Causes and Solutions

Model: 1999 Chevy Suburban Fault Code: P0405 Posted: 2008-05-01 14:28

I'm experiencing recurring OBD2 fault codes P0404 (Exhaust Gas Recirculation Circuit Range/Performance) and P0405 (Exhaust Gas Recirculation Sensor A Circuit Low) on my 1999 Chevy Suburban. After reviewing the code descriptions, I understand these relate to the EGR system performance and sensor readings. I'm new to diagnosing engine codes and would appreciate expert advice on possible causes. The issue persists — after clearing the codes, they return almost immediately. This suggests a recurring hardware or electrical problem rather than a temporary glitch. Thanks for any insights, Dave

Related fault codes
P0404P0405
Comments (3)
Anonymous 2008-05-02 06:58

A faulty EGR valve is a likely cause — particularly if the pintle is stuck open or there's an issue with wiring. This can lead to incorrect EGR flow and trigger both P0405 and P0404 codes.

Anonymous 2008-05-02 10:44

Some dealerships offer an EGR valve upgrade that includes a protective screen to prevent carbon buildup on the pintle, which can cause it to stick open. This may help resolve recurring P0400/P0405 issues in older models like the 1999 Chevy Suburban.

Anonymous 2011-02-07 21:04

For more technical details on P0405, refer to this OBD2 code reference: http://www.obd-codes.com/p0405