U3559

Air Inlet Pressure Sensor Circuit

Moderate severity

Generic electrical fault on the air inlet pressure sensor of the fuel cell air supply (cathode side, before compressor).

Common causes

Sensor failed
One of the most commonly reported causes for this code — check this first.
high
Typical part cost: $220-1650
Gateway module routing CAN messages incorrectly
Less common, but worth ruling out after the more likely causes.
low
Typical part cost: $220-1650
See all causes + fix costs
Create a free Wrenchify account to unlock the rest for U3559.
Unlock causes
Free forever · No credit card

First things to check

1Confirm the code with a scan tool and check for additional related codes.
2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.

Get the full step-by-step diagnosis

Create a free Wrenchify account to unlock the rest for U3559.

Unlock diagnosis

Free forever · No credit card

Related codes

See related trouble codes

Create a free Wrenchify account to unlock the rest for U3559.

Unlock related codes

Free forever · No credit card

Frequently asked questions

What does U3559 mean?

U3559 means "Air Inlet Pressure Sensor Circuit". It is a generic OBD-II code that points to a fault in the network / communication.

What are the most common causes of U3559?

sensor failed; gateway module routing can messages incorrectly; can terminating resistor (120 ω) drifted out of spec — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.

Can I keep driving with this code?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical. Use the Wrenchify app for a full diagnosis specific to your vehicle.

Get the full U3559 diagnosis for your vehicle

Year, make, model + step-by-step repair help — free plan included.

Diagnose U3559