OBD-II code P1404 indicates a problem in the circuit for Intake Air Temperature (IAT) Sensor B and/or a performance issue with the Exhaust Gas Recirculation (EGR) valve failing to reach or report its closed position. The powertrain control module (PCM) monitors IAT B and the EGR position feedback, and sets this code when the readings do not match expected values. This is commonly an emissions-related fault and is frequently seen on certain vehicle makes where the IAT B input is used to help validate EGR operation.
Carbon deposits building up in the EGR valve pintle or passages are the single most common reason the valve cannot seat fully in the closed position. This is the failure most mechanics encounter first.
An open, shorted, or corroded Intake Air Temperature sensor B circuit produces implausible temperature readings that the PCM interprets as a fault. Damaged pigtails and chafed harness sections are common.
If the integrated EGR valve position sensor reports a voltage outside its expected range, the PCM cannot confirm the valve is closed, even when the valve itself is mechanically sound.
Restricted coolant or exhaust passages leading to the EGR valve prevent the pintle from seating properly and can mimic a position performance fault.
A leaking vacuum line, weak vacuum signal, or low reference voltage to the EGR solenoid can prevent commanded movement, producing the same code.
The powertrain control module is occasionally implicated, but only after every sensor, wiring, and mechanical cause has been ruled out by direct testing.
No. Despite what some generic code readers or online posts suggest, P1404 is almost never caused by a bad computer. The fault overwhelmingly traces to a carbon-fouled EGR valve, a failed IAT B sensor, or wiring/connector damage. Replacing the PCM without first proving the inputs and outputs are correct is an expensive mistake.
In most cases the vehicle will still run, but you may notice rough idle, hesitation, stalling, or reduced fuel economy. The vehicle may also fail an emissions inspection. Driving short distances is usually fine, but the underlying cause should be repaired promptly to prevent catalytic converter stress from rich operation.
Yes. P1404 is associated with the EGR system, which is a federally controlled emissions component, and with intake air temperature sensing used in the emissions control strategy. The code typically counts as a readiness monitor failure until repaired.
Costs vary widely by vehicle, region, and whether the fix is a cleaning, a sensor, or a valve. The least expensive resolution is often a thorough EGR cleaning combined with an IAT sensor B inspection, while a full EGR valve replacement is more involved. Obtaining a confirmed diagnosis before authorizing any repair is the best way to control cost.