P0185: Fuel Temperature Sensor B Circuit
What to do
Usually driveable. Worth attending to on a diesel, where the supply-to-return temperature difference informs pump and injector diagnostics.
What this code means
A circuit fault in the second fuel temperature sensor. A second sensor appears where the system measures fuel at two points — typically supply and return — so the module can calculate how much heat the injection system is putting into the fuel. That difference is itself a diagnostic signal on common-rail diesels.
Likely causes
Start here
- Faulty fuel temperature sensor · moderate
- Corroded or loose connector · easy
- Open circuit in sensor wiring · moderate
Less common
- Road damage to underfloor wiring · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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