P0186

Universal

Fuel Temperature Sensor B Circuit Range/Performance

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

The engine computer monitors the signal from Fuel Temperature Sensor B to estimate fuel temperature. P0186 means the signal is outside the expected range or does not behave plausibly. The cause could be the sensor, its wiring or connectors, or another issue affecting the signal; the code alone does not prove the sensor needs replacement. The vehicle may show a warning light, run differently, or have no noticeable symptoms. Exact function and diagnostic procedures depend on the vehicle.

Report an error with this code

⚠️ Before You Begin (Safety First)

If the engine stalls, runs unpredictably, or the vehicle feels unsafe to drive, stop in a safe place and arrange diagnosis. Do not open fuel lines or work around leaking fuel; fuel can ignite. If you notice a fuel leak or strong fuel odor, shut the vehicle off when safe and seek professional help.

Common Symptoms

  • The malfunction indicator lamp may illuminate when the control module detects an implausible or out-of-range sensor signal.
  • There may be no noticeable change in vehicle operation if the system can compensate for the missing or unreliable temperature information.
  • Some vehicles may show changes in starting or engine operation if fuel-temperature information is used in engine management.
  • A scan tool may show a fuel-temperature value that is implausible, erratic, or inconsistent with other temperature readings.

Common Causes

  • Fuel Temperature Sensor B may be faulty or producing an inconsistent signal.
  • A damaged, loose, corroded, or contaminated connector may interrupt or distort the sensor signal.
  • Wiring may be chafed, broken, shorted, or otherwise damaged.
  • A problem with the sensor circuit's power, ground, or signal path may cause an out-of-range reading.
  • A control-module or related circuit issue is possible, but should be considered only after the sensor and wiring are checked.

Diagnostic Steps

  1. Record the code and any other stored codes before clearing anything; related codes and freeze-frame data can help identify when the condition occurred.
  2. With the vehicle off, visually inspect accessible wiring and connectors associated with Fuel Temperature Sensor B for looseness, corrosion, damage, or signs of fuel leakage. Do not disconnect fuel lines.
  3. If a scan tool is available, observe the fuel-temperature reading and check whether it is stable and plausible for the vehicle's conditions. Sensor location and expected readings vary by vehicle.
  4. If the connector or wiring is visibly damaged, or the reading is implausible, consult vehicle-specific service information or a qualified technician before attempting electrical tests or replacing parts.
  5. After any confirmed repair, clear the code only when appropriate and check whether it returns during normal operation.

When to Call a Professional

Start by checking all stored codes and freeze-frame data, then inspect the sensor circuit and compare scan-tool fuel-temperature data with other available temperature readings under suitable conditions. Test the sensor signal, wiring, connectors, and circuit power or ground as applicable, using vehicle-specific service information. Confirm the fault before replacing parts.

Compare component listings

Confirm diagnosis and vehicle fitment before buying. A listing does not prove that a part needs replacement. We may earn a commission from qualifying purchases.

Search Amazon Search eBay

Commonly Asked Questions

Does P0186 prove that Fuel Temperature Sensor B has failed?

No. The code identifies an out-of-range or implausible circuit signal. The sensor, connector, wiring, or another part of the circuit could be responsible.

Can I keep driving with P0186?

If the vehicle runs normally and there is no fuel leak or strong fuel odor, arrange diagnosis soon and monitor for changes. Stop driving if it stalls, becomes unsafe, or fuel is leaking.

What does the computer check for this code?

It monitors the Fuel Temperature Sensor B signal and detects when its range or behavior is not plausible. The exact monitoring strategy depends on the vehicle.

Should I replace the sensor first?

Not without testing. Inspect the connector and wiring and verify the scan data and circuit before choosing a repair.

Where is Fuel Temperature Sensor B located?

Location and sensor arrangement vary by model, year, and engine. Use vehicle-specific service information to identify the correct component.

Browse Available Code Guides

Previous and next available guides in database record order, across makes. Adjacent entries may share a code number and do not necessarily describe related faults.