P1404 Diagnostic Code for 2003 Kia Spectra 1.8L - Differential Pressure Issue and Fix

Model: 2003 Kia Spectra 1.8L Fault Code: P1404 Posted: 2012-09-05 18:14

My 2003 Kia Spectra 1.8L has recently triggered a P1404 diagnostic code, which reads 'Differential pressure not plausible (hose line defective) - Diesel'. This issue has been present for some time but previously went away before I could take it to the shop. It has now returned after being stable for about a month, coinciding with my upcoming vehicle inspection. I already replaced the purge valve located behind the engine, and after clearing the code, it immediately reappeared. The car has received regular maintenance and is currently at 110,000 miles, with only one winter in salt conditions. I have found limited information on resolving this specific P140-4 error for this model. Any insights or recommended troubleshooting steps would be greatly appreciated, especially regarding potential hose line issues or related components.