Engine Oil Pressure Sensor Voltage Low
The engine oil pressure sensor is reading a low voltage signal.
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)
The oil pressure sensor measures how much oil is circulating in the engine. If it sends a low voltage, it means there's not enough oil pressure for proper lubrication, which can harm the engine.
What the computer is actually seeing
The computer expects a voltage range from the sensor between 0.5V and 4.5V, with normal operating conditions showing around 2.0V to 3.5V at normal engine operation.
What a healthy reading looks like
Oil pressure should be between 20 PSI to 80 PSI, depending on engine speed and load, 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.
- 1Check the engine oil level. Add oil if below the minimum mark. Recheck codes after adding oil.
- 2Inspect the oil pressure sensor connector for damage, corrosion, or loose connections. Repair as necessary.
- 3Measure the voltage at the oil pressure sensor connector with the engine running. Expect 0.5V to 4.5V. If voltage is below 0.5V, proceed to the next step.
- 4Check the wiring continuity between the ECM and the oil pressure sensor. Look for shorts to ground or opens in the circuit.
- 5Replace the oil pressure sensor if previous checks are good and voltage readings are still incorrect.
Common causes
- Low oil level or old oil
- Bad oil pressure sensor
- Wiring issues or short circuit in the sensor circuit
- Oil passages blocked or restricted
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with SPN 855 active?
Moderately safe if you're not experiencing any performance issues, but fix it soon to prevent engine damage.
Will this code come back after I clear it?
If the underlying issue isn't resolved, yes it will return.
Why does SPN 855 sometimes pair with other codes?
Oil pressure issues can affect multiple systems, causing other codes related to oil temperature or engine performance.
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