Fuel Level Sensor 1
Indicates a fault in the fuel level sensor circuit.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
There's a problem with the sensor that measures how much fuel is in the tank, which can lead to incorrect fuel readings.
What the computer is actually seeing
The engine control module (ECM) expects the fuel level sensor to send a voltage signal between 0.5 to 4.5 volts, depending on the fuel level in the tank. If the voltage falls outside of this range, the ECM sets SPN 674.
What a healthy reading looks like
0.5V indicates empty, 4.5V indicates full; typically should read anywhere from 1.0 to 4.0V during normal operation.
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.
- 1Step 1: Inspect the wiring and connectors for the fuel level sensor. Look for any signs of damage, corrosion, or loose connections. If found, repair or replace as necessary. Decision Point: If wiring/connector issues fixed, clear codes and retest. If not, proceed to next step.
- 2Step 2: Measure the voltage output from the fuel level sensor with a multimeter while the key is in the ON position (engine off). Expected values should be between 0.5 to 4.5 volts. Decision Point: If voltage is out of range, replace the fuel level sensor. If within range, proceed to next step.
- 3Step 3: Check the ECM for potential fault codes related to other sensors or components. If there are additional faults, troubleshoot them first. Decision Point: If no other faults, the ECM may be faulty and need replacement.
Common causes
- Faulty fuel level sensor
- Broken or shorted wiring
- Corroded connector terminals
- Faulty ECM
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate severity; while you can drive, be careful of running out of fuel unexpectedly.
Will this problem come back after I fix it?
If the core issue is properly addressed (like a bad sensor or wiring), it should not return.
Why does this code appear with other fuel system codes?
Fuel level issues often correlate with other components in the fuel system. Intermittent faults or wiring issues can affect multiple sensors.
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