What are normal FTP voltages at atmospheric pressure?

GM ~1.5 V; Toyota/Lexus ~3.3 V; Honda/Ford ~2.5 V; Nissan/Infiniti 3.3–4.2 V (see table).

My sensor reads but doesn’t change under purge—bad sensor or system?

Verify purge solenoid operation and sealing; look for ≈50–500 mV voltage change under induced vacuum/pressure.

Do I need a scan tool to test the FTP?

No, you can back-probe the signal wire with a multimeter. A scan tool just simplifies readout.

Why do GM FTP readings move opposite of other makes?

GM FTP increases with vacuum and decreases with pressure; most other brands are the reverse.

Can a loose gas cap or topping off affect results?

Yes, equalize system pressure (remove/replace cap) before testing.

EVAP Fuel Tank Pressure Sensor Test — Step-by-Step DIY for P0452–P0453

Tools: Scan tool (or multimeter), back-probe leads
Difficulty: 2/5 Time: 15–25 minutes
Last Updated: October 2025

Common Symptoms of a Bad FTP Sensor

Check Engine Light with P0452, P0453, or P0454
Hard start or long crank after refueling
EVAP readiness monitor not completing
Incorrect or unstable pressure readings on scan tool
Strong fuel smell or rough idle during EVAP purge

Fuel Tank Pressure Sensor Operation

The Fuel Tank Pressure (FTP) sensor monitors the pressure or vacuum in the EVAP system. It is a 3-wire sensor that includes a 5-volt reference, ground, and signal circuit.
As system pressure changes, the sensor outputs a corresponding voltage to the engine control module (ECM), allowing it to detect leaks and verify EVAP component operation.

Fuel Tank Pressure Sensor Test

1. Check Sensor Inputs

Unplug sensor connector.
Turn the key ON (engine off).
Verify 5-volt reference and ground on the correct pins using a multimeter.

Tip: Check service information or contact GoTech Techline for pinout details.

2. Check Sensor Output

Reconnect sensor.
With key ON, engine OFF, read FTP voltage on a scan tool. (See table below for normal ranges.)

Tip: Use back-probe leads so you can read the signal wire without damaging the connector.

Without a scan tool, back-probe the signal wire and check voltage using a multimeter.
While monitoring, activate the purge solenoid via scan tool or jumper wire.
Look for a small voltage change (~50–500 mV). This confirms the sensor responds to pressure changes and isn’t stuck.

Tip: Some systems maintain slight pressure or vacuum. Remove the gas cap to equalize before testing.

FTP Voltage Reference Table by Make

Make	Typical FTP Voltage (Atmospheric)
GM	~1.5 V (rises with vacuum)
Toyota/Lexus	~3.3 V
Honda/Ford	~2.5 V
Nissan/Infiniti	3.3–4.2 V
Hyundai/Kia	~2.5–3.0 V

Vehicles This Applies To

GM, Ford, Toyota/Lexus, Honda/Acura, Nissan/Infiniti, Hyundai/Kia, and most OBD-II vehicles with EVAP monitoring systems.