The OBD2 code P0450 stands for “EVAP (Evaporative Emission Control System) Pressure Sensor/Switch Malfunction.” This code is triggered when the engine control module (ECM) detects an issue with the signal from the EVAP system pressure sensor. Understanding this code is crucial for maintaining your vehicle’s emission system and ensuring it runs smoothly.
P0450 quick overview
| Meaning | P0450: EVAP Control System Pressure Sensor/Switch Malfunction |
| Is it serious? | Yes, it can lead to increased emissions, fuel consumption, and possibly a failed emissions test. |
| Possible causes | – Faulty EVAP system pressure sensor – Wiring or connector issues (shorts, opens, corrosion) – Blocked EVAP system vent or purge lines – Faulty vent or purge valves |
| How to diagnose? | Check the EVAP pressure sensor for proper operation with vacuum and pressure tests. Inspect wiring and connectors for damage, corrosion, or disconnection. Monitor the sensor’s voltage to identify abnormal readings. Examine the vent system for blockages or stuck valves. Replace faulty components like the canister vent solenoid or pressure sensor if necessary. |
P0450 Meaning
In simpler terms, the P0450 code means your car’s computer thinks there’s a problem with a sensor that checks the fuel system’s vapor pressure. This sensor helps control pollution by managing vapors from your fuel tank. If something’s wrong, like a bad sensor, a wire issue, or a clog in the system, your car might pollute more, use more fuel, or even have trouble filling up with gas. Mechanics will test this system, look for blockages, and might replace some parts to fix it.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
How to fix P0450 – learn from mechanics
I looked into P0450 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.
Case #1: Nissan
Vehicle information 1998 Nissan 200SX 1.6L
Issue + repair history
- CEL on and very slow gas filling.
- Checked all EVAP systems, found no issues.
- Acted like a basic plugged vent in the tank.
- Found TSB on canister vent valve, tested good.
Other OBD2 Codes + Test Results
- PO450: Evap system pressure sensor problem
- EPS shows good adjustment with vacuum and pressure tests
Mechanic suggestions
- Monitor EVAP pressure sensor while operating purge volume control valve.
- Check for vent blockage by blowing through hose or removing and inspecting for restrictions.
- Check rubber hoses and connections for clogs, bends, or disconnections.
- Inspect evap canister and purge volume control solenoid valve for malfunctions.
- Check for ORVR valve issues if applicable.
- Ensure vent control valve is not stuck when power is supplied.
- Inspect vent tube to atmosphere for nests or blockages.
Final fix Replaced canister vent solenoid.
Case #2: Mercedes
Vehicle information 1999 Mercedes-Benz E320 4Matic 3.2L
Issue + repair history
- CEL on, P0450 code.
- Sensor voltage reads 4.91 volts, with or without connector plugged in.
- Sensor also reads 83 mbar.
- Replaced sensor assembly but same readings persisted.
- Fuel tank near empty, no other codes stored.
Other OBD2 Codes + Test Results
- P0450: Fuel tank pressure sensor (B4/3)(B4/4)
Mechanic suggestions
- Check signal wire from tank pressure sensor for a short to ground.
- Measure voltage signal from pressure sensor at the ME.
- If voltage is the same at the ME as at the sensor, likely issue with the ME.
Final fix Discovered chewed signal wire due to mouse nest. Repaired wire, cleared codes, scanned data showing 0 mbars and 3.0 volts. Vehicle back on the road.
Case #3: Toyota
Vehicle information 1998 Toyota Sienna LE 3.0L
Issue + repair history
- Intermittent failure with codes P0441 and P0450.
- Lab scoped evap pressure sensor circuit at ECM, showed good.
- Checked voltage at connector E6 terminals 1 and 22, found 4.9 volts.
- Checked VSV for pressure sensor operation, found good but unclear if ECM is sending signal.
- Diagnostic chart suggested ECM replacement, uncommon failure.
- Additional code P0446 set during further diagnosis.
- Discovered kinked vent line from canister to air cleaner housing.
Other OBD2 Codes + Test Results
- P0441: Evap Control System Incorrect Purge Flow
- P0446: Evap Control System Vent Control Circuit Malfunction
- P0450: EVAP Control System Pressure Sensor Malfunction
- Evap Pressure Sensor: 3.73 volts with no vacuum, 1.7 volts with .59 inches of vacuum
Mechanic suggestions
- Common failure with charcoal canister and purge valve.
- Replace vapor canister assembly and purge/vent solenoids.
- Consider intermittent failure on tank pressure sensor, likely resolved with new canister.
- Check for TSBs, ensure latest versions are reviewed.
- Check tank inlet for corrosion and replace canister with related switches and valves.
- Blow out evap lines/hoses between front and back of the car.
Final fix Repaired kinked vent line from canister to air cleaner housing.
How to diagnose P0450
I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.
| Diagnostic Step | Brief Explanation |
|---|---|
| Monitor EVAP pressure sensor | Check the sensor’s response to ensure it’s working correctly. |
| Check for vent blockage | Ensure the vent system to the atmosphere is clear of any nests or debris. |
| Inspect wiring and connectors | Look for any damage or corrosion that might affect sensor readings. |
| Replace canister vent solenoid | If the solenoid is faulty, replacing it can solve the issue. |
| Repair damaged wiring | Fix any chewed or damaged wires to restore proper sensor function. |
| Blow out EVAP lines/hoses | Clear any obstructions in the EVAP system to ensure smooth flow. |
| Replace vapor canister assembly | If the canister or related valves are faulty, a replacement might be necessary. |
Remember, dealing with EVAP system issues can be tricky. If you’re not comfortable diagnosing or fixing these problems, it’s always a good idea to consult a professional mechanic.
Car Diagnostics Training
- Car Electrical basics
- OBD-II scanner basics
- How to use an OBD reader
- Introduction to a Bi-directional Scan tool
- OBD scanner buyer’s guide + discounts
I test OBD-II scanners and make DIY Engine diagnostics guides to help you solve your car problems without having to depend on the mechanic. A lot of them will try to scam you or are just no help at all. About Juraj Lukacko