What Does P1404 Mean?
This code indicates either an Intake Air Temperature sensor circuit malfunction on circuit B (on vehicles with dual IAT sensors), or an EGR valve position sensor indicating the valve is not achieving proper closed position when commanded. The dual nature depends on manufacturer and model year.
Common Causes
35%
Carbon buildup preventing EGR valve from fully closing
25%
Failed EGR valve position sensor or potentiometer
20%
Failed or out-of-range IAT sensor (circuit B)
12%
Damaged wiring or connector in EGR position sensor circuit
8%
Mechanically stuck or binding EGR valve stem
Diagnostic Steps
1
Step 1: Monitor EGR valve position sensor voltage at idle (should indicate fully closed, typically <0.5V)
2
Step 2: Command EGR valve open/closed with scan tool and verify smooth position change
3
Step 3: Remove EGR valve and inspect for carbon buildup on pintle and seat, clean or replace as needed
4
Step 4: If IAT-related, check sensor resistance against temperature chart and wiring continuity
5
Step 5: Verify EGR valve operates freely without binding and returns to closed position with spring pressure
Estimated Repair Cost
$120 - $450
Parts + labor, varies by vehicle and location
This code indicates either an Intake Air Temperature sensor circuit malfunction on circuit B (on vehicles with dual IAT sensors), or an EGR valve position sensor indicating the valve is not achieving proper closed position when commanded. The dual nature depends on manufacturer and model year.
The most common cause of P1404 (IAT - B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance) is: Carbon buildup preventing EGR valve from fully closing
Typical repair costs for P1404 range from $120 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive but may experience rough idle, stalling, or increased NOx emissions. Vehicle will likely fail emissions testing.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1404 to identify the root cause.
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Quick Info
Category
Powertrain
System
Emissions Control System (EGR) or Air Intake System
Difficulty
Type
Manufacturer
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