P0189

Universal

Fuel Temperature Sensor B Circuit Intermittent

Definition source: General OBD-II reference catalog
Definition verification: Not independently verified for display.
Time: Varies by diagnosis and vehicle | Diagnostic difficulty: Medium
Medium Severity

Fuel Temperature Sensor B reports fuel temperature to the vehicle’s control system. This code means the signal or circuit was detected as intermittent, so the reading may sometimes be missing or unreliable. The warning light may be the only noticeable effect, though inaccurate data can affect engine operation on some vehicles. The code does not by itself prove that the sensor needs replacement.

Report an error with this code

⚠️ Before You Begin (Safety First)

This fault alone does not usually require stopping immediately. Stop driving if the vehicle stalls, loses power severely, or becomes unsafe to control. If you notice fuel leaking or smell fuel, stop in a safe place, switch off the engine, and arrange professional help.

Common Symptoms

  • The malfunction indicator lamp may illuminate, sometimes intermittently.
  • There may be no noticeable change in how the vehicle runs.
  • If unreliable temperature data affects engine control, rough running or changes in performance may occur; this depends on the vehicle.

Common Causes

  • A loose, corroded, or damaged connector may interrupt the sensor circuit intermittently.
  • Chafed, stretched, or internally damaged wiring may cause the signal to drop out as the harness moves or warms.
  • Fuel Temperature Sensor B may have an intermittent internal fault.
  • A problem in the circuit’s power, ground, or signal path may cause an unstable reading.
  • A control-module circuit issue is possible but should be considered only after the sensor and wiring are tested.

Diagnostic Steps

  1. Check the vehicle’s manual or service information to confirm the code and locate the applicable Fuel Temperature Sensor B circuit for your model, year, and engine.
  2. With the vehicle safely parked and the ignition off, visually inspect accessible wiring and connectors for looseness, corrosion, rubbing, or damage. Do not pull on wires or touch hot or moving parts.
  3. Use a scan tool, if available, to review stored codes and freeze-frame information. Note whether other codes point to a shared wiring or power issue.
  4. If live data is available, observe the Fuel Temperature Sensor B reading for dropouts or implausible changes. Do not assume a particular reading is correct without vehicle-specific service information.
  5. If the code returns or the wiring is not safely accessible, have a technician test the circuit using the correct wiring diagram and procedures.

When to Call a Professional

Compare Fuel Temperature Sensor B scan data with other available temperature readings and check whether the signal drops out while monitoring the circuit. Inspect the connector and harness, then test the sensor’s power, ground, and signal circuits using the vehicle’s wiring diagram and service procedure. Consider a control-module fault only after the sensor and wiring have been checked.

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Commonly Asked Questions

Does P0189 mean Fuel Temperature Sensor B must be replaced?

No. The code identifies an intermittent circuit condition, not a confirmed failed part. A connector, wiring, power, ground, or signal-path issue can produce the same condition.

Can I keep driving with P0189?

If the vehicle runs normally and there are no fuel leaks or other serious symptoms, cautious driving to arrange diagnosis may be reasonable. Stop if it stalls, loses power severely, or becomes unsafe to control.

What does “intermittent” mean in this code?

It means the circuit condition may come and go rather than remaining continuously present. Movement, vibration, heat, or a poor connection can sometimes contribute, but testing is needed to identify the cause.

Can a bad connector cause this code even if the sensor is good?

Yes. A loose or corroded connection, or damaged wiring, can interrupt the sensor signal. The sensor and its circuit should be checked before deciding what to replace.

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