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P0183 — Fuel Temperature Sensor Circuit High

Generic OBD-II · all makesPowertrain (engine & transmission)

P0183 indicates the engine computer is seeing a voltage from the fuel temperature sensor circuit that is higher than expected, typically suggesting an open circuit or poor connection. The sensor helps the computer adjust fuel delivery based on fuel temperature. A high-input code usually points to the sensor, wiring, or connector rather than the computer.

Symptoms

What causes it — most likely first

1. Failed fuel temperature sensor

The sensor has failed open internally, producing an out-of-range high voltage signal to the PCM.

2. Open or shorted wiring in sensor circuit

A broken wire or short to voltage between the sensor and PCM can cause the signal to stay high.

3. Corroded or loose sensor connector

Poor terminal contact or corrosion at the fuel temperature sensor connector can interrupt the signal path.

4. Corroded or loose PCM connector

Corrosion or poor contact at the engine computer connector can affect the sensor signal input.

5. Faulty PCM/ECM

Internal failure of the engine computer input circuit is possible but very rare for this code.

How it's diagnosed

  1. Record freeze frame data and verify the code with a scan tool.
  2. Visually inspect the fuel temperature sensor connector and wiring for damage, corrosion, or loose pins.
  3. Disconnect the sensor and test its resistance across the terminals, comparing to specified values for temperature.
  4. Check the sensor circuit wiring for opens, shorts to voltage, or shorts to ground using a multimeter.
  5. Perform a wiggle test on the harness while monitoring live sensor data to locate intermittent faults.
  6. If sensor and wiring test normal, inspect the PCM connector; only consider PCM testing after all external causes are ruled out.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make

Vehicles this code applies to

The definition is universal; the diagnostics are engine-specific. Open your vehicle for the codes documented for it:

1998 Mazda B-Series1999 Mazda B-Series

Frequently asked

Is it safe to drive with P0183?

In many cases the vehicle can be driven, but the code should be diagnosed promptly because fuel delivery adjustments may be affected.

Does a high-input code mean the sensor is bad?

It often does, but an open or shorted wire or corroded connector can produce the same reading, so wiring should be tested before replacing the sensor.

Should I replace the PCM for P0183?

No. A high-input fuel temperature sensor code is almost never caused by the PCM. Replacing the computer without proving a wiring or sensor fault is usually incorrect.

Can a bad fuel temperature sensor cause poor running?

It can contribute to incorrect fuel metering and starting or idle issues, though many vehicles show no obvious drivability symptoms beyond the Check Engine Light.