P0450: EVAP pressure sensor malfunction
Evaporative emission control system pressure sensor malfunction
Severity: Monitor
P0450 is an emissions-monitor fault on the EVAP pressure sensor circuit. It stops the leak test from running but does not change how the car drives.
P0450 in short
P0450 means the engine computer sees a fault in the EVAP pressure sensor, the sensor that reads vapour pressure in the fuel tank system. Wiring, a corroded connector or the sensor itself are the usual suspects. The car normally drives fine, but it will fail an emissions test until it is fixed.
The EVAP system uses a pressure sensor to tell the computer how much pressure or vacuum is in the fuel vapour lines. The computer needs that reading to run its leak tests.
One published description says the code sets when the sensor voltage stays below 0.5 volts or above 4.8 volts for more than half a second, which points to an open or shorted circuit rather than a leak. Exact limits differ by make.
Because the fault is in the sensor circuit, check the wiring, connector and sensor before replacing leak-related parts such as the fuel cap.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Open or shorted signal wire, poor ground or corroded connector
Common general cause- Why it ranks here
- The trigger is a voltage outside the normal range, which an open, short, bad ground or wet connector produces.
- What would change this
- Rises if the connector is wet or corroded or the wire is chafed. Falls if wiring and ground test good.
Cause 2: EVAP pressure sensor failed
Common general cause- Why it ranks here
- A failed sensor outputs a voltage outside its range and sets the same code.
- What would change this
- Rises if wiring tests good but the output does not follow applied vacuum.
Cause 3: Blocked EVAP hose causing abnormally high tank pressure
Possible — needs testing- Why it ranks here
- The source lists a blocked hose as a cause that can push tank pressure past the sensor range, so it is a less common cause to test after the circuit.
- What would change this
- Rises if tank pressure reads high with the cap off.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Inspect the EVAP pressure sensor connector and wiring for corrosion, water, pushed-out pins or chafing.
IfConnector is corroded or wiring is damaged
It meansRepair the circuit, clear the code and recheck.
Points to: Open or shorted signal wire, poor ground or corroded connector
IfWiring looks good
It meansCheck the sensor's reference voltage, ground and output.
Step 2: With a multimeter, check the 5-volt reference and ground at the sensor, then read the output (about 3 volts is described as normal) and see whether it changes when vacuum is applied.
Warning:Fuel vapour is flammable: no sparks or open flame near the tank, and apply only gentle hand vacuum so the sensor diaphragm is not damaged.
IfReference or ground is missing
It meansWiring or computer-side fault; trace the circuit.
Points to: Open or shorted signal wire, poor ground or corroded connector
IfReference and ground good but output is out of range or does not respond
It meansThe sensor is the likely fault.
IfSensor responds normally but pressure reads high on its own
It meansLook for a blocked EVAP hose.
Points to: Blocked EVAP hose causing abnormally high tank pressure
Symptoms
- Check engine light with no change in how the car drives
- Emissions test not ready or failed
- Occasional fuel odour Gets more serious: stop and have it checked.
How to fix
Parts and cost context
- Fuel tank pressure sensor:Rule out the connector and wiring before buying the sensor.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0450 yet. The causes and tests above apply across vehicles.
Related codes
P0450 questions
Is it safe to drive with P0450?
Usually yes. It is an emissions-monitor fault and the car should drive normally, but have it checked if you smell fuel.
Sources and review
- P0450 Code: EVAP Pressure Sensor Circuit Malfunction
- On-Board Diagnostic Trouble Codes (generic code title list)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error