FMI 16 - Secondary Fuel Pressure - Below Normal Operating Range
The secondary fuel pressure is too low for proper engine operation.
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What it means (plain English)
The engine needs fuel pressure to run properly, and this code means it's not getting enough pressure from the secondary fuel system, which could lead to poor performance or stalling.
What the computer is actually seeing
The engine control unit (ECU) expects secondary fuel pressure to be within a specific range, typically around 50-70 psi. If it detects pressure lower than 45 psi, it sets this fault code.
What a healthy reading looks like
Secondary fuel pressure should be between 50 and 70 psi under normal operating conditions.
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.
- 11. Check the wiring and connectors for the fuel pressure sensor; look for frayed wires or corroded connectors. If damaged, repair or replace.
- 22. Verify fuel levels in the tank; ensure there's enough fuel for the pump to operate correctly. If low, add fuel and retest.
- 33. Connect a fuel pressure gauge to the secondary fuel system; measure pressure at idle and under load. Is it below 50 psi? Yes: proceed to step 4, No: further investigation needed for possible sensor or ECU issue.
- 44. Inspect the fuel filter; replace it if it shows signs of clogging or restriction. After replacement, clear the code and retest.
- 55. Check the fuel pump operation; listen for proper function while the key is on and during cranking. If not working, replace the fuel pump.
Common causes
- Clogged fuel filter
- Damaged or leaking fuel lines
- Faulty fuel pump
- Blocked fuel return line
- Defective pressure sensor
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not recommended to drive, as low fuel pressure can lead to stalling and poor engine performance.
Will the code come back after repair?
If the root cause is properly addressed, the code should not return.
Why does this code show up with low voltage issues?
Low voltage can affect the fuel pump operation, leading to insufficient fuel pressure, which may trigger this code.
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