FUEL TANK PRESSURE SENSING ERROR
Fuel tank pressure sensor malfunction or poor connection.
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What it means (plain English)
The fuel tank pressure sensor measures how much pressure is in the fuel tank. If it doesn't work right, it sends wrong information to the engine computer, which can cause fuel system issues.
What the computer is actually seeing
The engine control module (ECM) expects a specific voltage from the fuel tank pressure sensor, typically around 0.5 to 4.5 volts, depending on the fuel tank pressure. If it sees a constant voltage signal outside of this range (like 0 volts or over 4.5 volts), it triggers the fault code.
What a healthy reading looks like
Expected voltage range from the sensor is 0.5V (at about -4 inches of water pressure) to 4.5V (at about +3.5 inches of water pressure).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check the wiring and connectors for the fuel tank pressure sensor. Repair any damage or poor connections. If okay, proceed to step 2.
- 2Measure the voltage at the fuel tank pressure sensor connector with the key on (engine off). It should be between 0.5V and 4.5V.
- 3If voltage is not in range, replace the fuel tank pressure sensor. If within range, check for vacuum leaks in the fuel tank system.
Common causes
- Faulty fuel tank pressure sensor
- Wiring harness damage or poor connection
- Vacuum leak in the fuel tank or system
- Corroded connectors or pins
- ECM calibration issues
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe but may affect fuel efficiency and emissions. Get it checked soon.
Will this code come back after resetting?
It can if the underlying issue isn't fixed, like a faulty sensor or bad wiring.
Why does this code pair with SPN 6786?
SPN 6786 often indicates related issues with the fuel tank pressure sensor and its operation.
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