P0450 means the ECU has detected an abnormal or invalid signal from the EVAP system pressure sensor — the sensor that monitors fuel tank pressure as part of the evaporative emissions system. When this sensor fails or its circuit has issues, the EVAP system cannot run leak tests or regulate purge/vent operations correctly. This can lead to fuel odors, incorrect EVAP operation, and emissions failures. In this guide, you’ll learn what P0450 means, the common causes, how to diagnose it properly, and the repairs that typically resolve the problem.
What Does P0450 Mean?
P0450 sets when the ECU expects a specific pressure or voltage range from the fuel tank pressure (FTP) sensor but receives a signal that is out of range, stuck, erratic, or inconsistent. The FTP sensor measures fuel vapor pressure inside the tank and is crucial for EVAP leak detection. When the sensor fails, the ECU cannot perform the EVAP self-test, so it triggers P0450.
This code is not a leak code. Instead, it is an electrical or sensor-based fault, typically caused by wiring damage, a faulty pressure sensor, or contamination inside the EVAP system. It commonly appears on vehicles with aging fuel tanks, rusted connectors, or EVAP components exposed to moisture.
Quick Reference
- OBD-II Family: P-Code (Powertrain)
- Scope: Generic
- System: EVAP (Evaporative Emission Control)
- Difficulty Level: Intermediate
- Estimated Repair Cost: €60–€200
- Last Updated: 2025-11-24
Real-World Example / Field Notes
On Toyota, Hyundai, and Ford vehicles, P0450 frequently appears when the fuel tank pressure sensor becomes contaminated with fuel, water, or rust particles. One Toyota Camry case involved a failing FTP sensor stuck at a fixed voltage no matter the tank pressure. The ECU flagged P0450 because the sensor never changed output during purge or vent commands. Replacing the FTP sensor solved the issue instantly. On GM vehicles, corroded wiring at the tank connector is a very common cause.
Symptoms of P0450
- Check Engine Light: Always appears when the sensor signal is out of range.
- Fuel smell: Due to improper EVAP regulation.
- Difficulty refueling: If the vent and purge systems cannot adjust correctly.
- Failed emissions test: EVAP monitors cannot complete.
- Rough idle or hesitation: Rare, but possible if purge flow is affected.
- Tank pressure readings stuck or erratic: Seen in live data during diagnostics.
Common Causes of P0450
Most Common Causes
- Failed fuel tank pressure (FTP) sensor.
- Corroded or damaged wiring at the tank or frame rail.
- Faulty electrical connector at the pressure sensor.
- Water intrusion or contamination in the sensor housing.
- Incorrect voltage reference or ground to the sensor.
Less Common Causes
- Cracked fuel tank causing abnormal pressure readings.
- Charcoal canister failure affecting pressure regulation.
- Aftermarket sensor with incorrect calibration.
- ECU driver/feedback fault (rare).
- Vent or purge valve stuck, creating incorrect pressure readings.
Diagnosis: Step-by-Step Guide
Start by reading live data from the pressure sensor and verifying whether its signal changes during purge and vent operations.
Tools You’ll Need: OBD-II scanner with live data, multimeter, wiring diagram, smoke machine (optional), vacuum/pressure pump, and basic tools.
- Check pressure sensor live data. Voltage should typically vary between ~0.5–4.5V. Stuck or flat readings indicate failure.
- Inspect the sensor connector. Look for corrosion, bent pins, water, or loose terminals.
- Test reference voltage. Confirm the 5V supply from the ECU is present.
- Test sensor ground. A poor ground causes erroneous readings.
- Wiggle-test the harness. Observe live data for intermittent drops or spikes.
- Apply vacuum/pressure manually. The sensor voltage should change smoothly with pressure.
- Inspect EVAP vent and purge valves. A stuck valve can mimic a faulty pressure reading.
- Perform a smoke test. Ensure there are no severe leaks causing misleading pressure readings.
- Check for tank damage. Rusted or dented tanks can distort pressure feedback.
- Evaluate freeze-frame data. Helps determine load, fuel level, and temperature when the fault occurred.
Pro Tip: If the pressure sensor voltage remains at exactly 0V, 5V, or a fixed midpoint regardless of pressure changes, the sensor is either unplugged, shorted, or internally failed.
Possible Fixes & Repair Costs
- Replace the fuel tank pressure sensor: Most common fix (€60–€150).
- Repair wiring or connectors: Fixes voltage or ground issues (€10–€60).
- Replace charcoal canister: If debris or pellets clog the pressure reference line (€120–€180).
- Clean sensor connector: Removes corrosion and improves signal quality (€0–€10).
- Replace EVAP vent or purge valve: If they cause abnormal pressure readings (€40–€120 each).
- Replace ECU (rare): Only after verifying all other components and wiring (€200–€400).
Always verify the sensor’s live data behavior before replacing components — incorrect pressure readings are the core cause of P0450.
Can I Still Drive With P0450?
Yes, you can still drive, as the EVAP system does not directly affect engine performance. However, you may experience fuel odors or refueling difficulties, and the vehicle will fail an emissions test. Repair the issue soon to restore proper pressure monitoring and EVAP function.
Related Codes
- P0474 – Exhaust Pressure Sensor Intermittent
- P0473 – Exhaust Pressure Sensor High
- P0472 – Exhaust Pressure Sensor Low
- P0471 – Exhaust Pressure Sensor Range/Performance
- P0470 – Exhaust Pressure Sensor
- P0469 – EVAP Purge Flow Sensor Circuit Intermittent
- P0468 – EVAP Purge Flow Sensor Circuit High
- P0467 – EVAP Purge Flow Sensor Circuit Low
- P0466 – EVAP Purge Flow Sensor Circuit Range/Performance
- P0465 – EVAP Purge Flow Sensor Circuit
Key Takeaways
- P0450 indicates a fault with the EVAP system’s pressure sensor signal or circuit.
- Most common causes include a bad FTP sensor or wiring issues at the tank area.
- Driving is safe, but emissions testing will fail until repaired.
- Live data testing quickly reveals whether the sensor is functioning properly.
FAQ
What causes P0450 most often?
Typically a failed fuel tank pressure sensor or corroded wiring near the sensor. Moisture intrusion is extremely common in older vehicles.
Is P0450 a serious code?
Not for drivability, but it prevents EVAP leak testing from running and will cause emissions failures. It should be diagnosed soon to avoid fuel odors or refueling issues.
Can a bad gas cap cause P0450?
No. Gas caps cause leak codes like P0442 or P0455. P0450 specifically indicates a pressure sensor or circuit issue.
How do you diagnose a bad EVAP pressure sensor?
Check live data, verify 5V reference and ground, test the sensor with applied vacuum/pressure, and inspect the connector for corrosion or loose pins.
Can I drive with a faulty EVAP pressure sensor?
Yes, but the EVAP system won’t function correctly and the Check Engine Light will stay on. You may fail emissions inspection until the issue is repaired.