P0450

EVAP System Pressure Sensor/Switch Circuit

Car Fault Codes Emissions & exhaust

Can you still drive? Yes, normally

Who can fix it? Needs a workshop

Typical repair time 30 minutes – 3 hours

Typical cost SAR 100 to 900

What it means

The engine computer has detected a fault in the EVAP pressure sensor circuit, usually called the fuel tank pressure sensor. The computer relies on this sensor to detect leaks, so if its signal is faulty the EVAP test cannot run accurately.

Symptoms4

Check engine light on.
Usually no driving symptoms.
Other EVAP codes may appear with it.
Failed emissions test.

Possible causes5

Corroded or loose sensor connector.
Failed fuel tank pressure sensor.
Open or shorted signal, reference or ground wire.
Wiring under the vehicle damaged by stones or chafing.
Short in another sensor sharing the same reference circuit.

How to diagnose5

Watch the sensor reading on a scan tool with the fuel cap off; it should be close to atmospheric pressure per the manufacturer specification.
Visually inspect the connector and wiring, especially near the tank.
Measure the reference voltage and ground at the sensor connector.
Check continuity of the signal wire between the sensor and the computer.
Move the wiring while watching the reading to find an intermittent fault.

How to fix5

Clean or repair the connector.
Repair open or shorted wiring.
Replace the tank pressure sensor if it is proven faulty.
Repair any other sensor pulling down the shared reference.
Clear the codes and drive until the EVAP self-test completes.

Repair cost

0–500

500–2,000

2,000–5,000

5,000+

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a connector or wiring repair, and rises when the sensor sits on top of the tank and the tank must be lowered to replace it.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions

What does the tank pressure sensor do?

It measures pressure or vacuum inside the EVAP system, and the computer uses it to tell whether the system is sealed or leaking.

Can I drive with this code?

Yes. It does not affect the engine, but the computer cannot test for leaks until it is fixed.

This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.

Report a mistake

Spotted something inaccurate? Tell us and we will review and correct it.