P0184 means the engine control module saw the fuel temperature sensor A signal change too fast or drop out for an instant. It is the intermittent member of the P018x family: P0180 (circuit), P0181 (range or performance), P0182 (low), P0183 (high), P0184 (intermittent). Several manufacturers define the trigger as a change of more than about 10 °C (18 °F) within 100 milliseconds, which no volume of fuel can do. That definition is the diagnosis: the fault is electrical.
Severity: low. Can you keep driving? Yes. On a gasoline engine the fuel temperature reading trims injector timing and, on flex-fuel engines, helps estimate ethanol content; losing it costs a little economy and turns on the light. On a diesel the module uses fuel temperature to correct injection quantity, and a bad reading can produce a slight power loss or rough idle, but no damage.
Which engines have fuel temperature sensor A
Not all. The sensor appears on: common-rail and older electronic diesels (Ford Power Stroke, GM Duramax, Ram Cummins, Volkswagen TDI), where it sits on the fuel filter housing, the fuel rail or the high-pressure pump; flex-fuel gasoline engines, where it is often built into the fuel composition sensor on the feed line; and some direct-injection gasoline engines, where it is on the low-pressure side near the high-pressure pump. If the scan tool shows P0184 on an engine with no fuel temperature sensor, re-read the code with the manufacturer's definitions.
The GM 3.0 L Duramax harness case
General Motors preliminary information PIT5751 (June to December 2020) for the 2020 Silverado 1500 and Sierra 1500 with the 3.0 L LM2 diesel lists P0181 through P0184 among dozens of codes, alongside rough running, misfires, low power, gauge sweeps and blown fuses, all traced to the engine harness chafing on under-hood components. The correction is to find the rubbed section, repair it wire to wire, and wrap the harness with anti-abrasion tape at the contact points. When P0184 arrives with a cluster of other intermittent codes, the harness is the cause, not the sensor.
Causes, in the order they are found
A chafed wire in the harness between the sensor and the module, as in the GM case.
A connector contaminated with fuel or water, or a terminal that has lost tension. The sensor sits on the fuel system where diesel or gasoline leaks land, and fuel wicks into connectors.
A shared ground or reference with resistance. If other sensors on the same 5-volt reference show intermittent codes, the fault is upstream.
The sensor, a thermistor with a cracked element or an internal open that shows under vibration. Less common than the wiring.
The module, last.
A diagnostic order
- Record the freeze frame and companion codes. Several intermittent codes at once mean a harness or a shared circuit.
- Watch fuel temperature live at idle: it should read close to ambient on a cold engine and rise slowly. A value that jumps while the engine sits still is a live fault.
- Wiggle-test the harness from the sensor to the module while watching the live value, especially where it crosses brackets, the fuel filter housing and the intake.
- Open the connector and look for fuel, corrosion or loose terminals.
- Check the two wires end to end with the module unplugged: continuity under an ohm, no short to ground or to the reference.
- Measure the sensor's resistance at a known temperature against the chart; compare with the coolant sensor's behavior if no chart is available.
- Repair the wire or connector, or replace the sensor only if it measured wrong, then clear and verify over several warm-up cycles.
Frequently asked questions
Can I drive with a P0184 code?
Yes. The fuel temperature reading is a correction input, not a control input. Expect a small economy penalty or a slightly rough idle on a diesel, and the check engine light.
Is P0184 the fuel temperature sensor?
Sometimes, but the code describes a signal that jumped faster than fuel can change temperature, which is an electrical fault. A chafed harness or a fuel-contaminated connector is more common than a failed sensor. GM's 3.0 L Duramax bulletin traces this and dozens of other codes to a rubbed engine harness.
Where is fuel temperature sensor A?
On diesels, on the fuel filter housing, the rail or the injection pump. On flex-fuel gasoline engines, usually inside the fuel composition sensor on the feed line. On some direct-injection engines, on the low-pressure line near the high-pressure pump. Many engines have no such sensor at all.
How much does it cost to fix P0184?
A wire repair or connector is usually under an hour. The sensor is an inexpensive part on most engines; on a diesel with the sensor in the filter housing it may come with the housing.
Related codes
- P0180 to P0183: fuel temperature sensor A circuit, range, low, high.
- P0185 to P0189: fuel temperature sensor B, the second sensor on engines with two.
- P0194: fuel rail pressure sensor intermittent, often stored with P0184 when a shared harness is chafed; see P0194.
The code number itself tells you the family and the domain; how to read an OBD2 code number explains what each character means, and what a trouble code does not tell you covers why a circuit code is not a part name.