Failed fuel temperature sensor integrated into the fuel pump; Damaged or chafed wiring between the FTS and the PCM; Corroded or loose electrical connector at the fuel pump or sensor; Open circuit in the sensor signal or ground return wire; Short to ground on the signal circuit; Contaminated or degraded fuel affecting sensor response; PCM internal fault on the sensor input circuit (rare)

DTC codes / Ford codes / P1186

P1186 · FordFTS Low Fuel Pump Temperature Sensor Low

Q: What does code P1186 mean?

FTS Low Fuel Pump Temperature Sensor Low. P1186 on Ford vehicles means the powertrain control module has detected a low signal from the Fuel Temperature Sensor (FTS) circuit, which on many Ford diesel applications is integrated into the fuel pump and monitors fuel temperature for injection timing and pump protection. The computer sets this code when the sensor voltage stays below the expected threshold for a calibrated time, indicating an open circuit, a short to ground, or a sensor that has failed low.

P1186 on Ford vehicles means the powertrain control module has detected a low signal from the Fuel Temperature Sensor (FTS) circuit, which on many Ford diesel applications is integrated into the fuel pump and monitors fuel temperature for injection timing and pump protection. The computer sets this code when the sensor voltage stays below the expected threshold for a calibrated time, indicating an open circuit, a short to ground, or a sensor that has failed low.

SystemPowertrain

Code typeFord specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or hesitation when the engine is cold
Reduced fuel economy or a rich-running condition
Hard starting or extended cranking, especially in cold weather
Intermittent stalling or a stumble under light throttle
Possible reduced engine power if the PCM enters a limp strategy

Common causes, most likely first

Failed fuel temperature sensor integrated into the fuel pump
Damaged or chafed wiring between the FTS and the PCM
Corroded or loose electrical connector at the fuel pump or sensor
Open circuit in the sensor signal or ground return wire
Short to ground on the signal circuit
Contaminated or degraded fuel affecting sensor response
PCM internal fault on the sensor input circuit (rare)

How to diagnose and fix it

Scan all modules and record freeze-frame data for P1186 to confirm the fault conditions
Visually inspect the FTS connector and harness for corrosion, chafing, or loose pins
Measure sensor resistance and compare to Ford specifications for the current fuel temperature
Backprobe the signal and ground circuits at the PCM to check for opens or shorts
Perform a voltage drop test on the sensor ground return circuit under load
Replace the fuel temperature sensor or fuel pump assembly if the sensor is proven faulty
Clear codes and verify the FTS signal reads correctly with a scan tool during a road test

What Ford techs check before replacing the pump

A low FTS signal often comes from a chafed harness near the fuel pump connector rather than a failed sensor, so always flex the harness while watching live data.
On many Ford diesel applications the fuel temperature sensor is not sold separately from the fuel pump, which makes proper circuit diagnosis critical before condemning an expensive assembly.
Fuel temperature readings that stay fixed at a very low value can indicate a shorted signal wire to ground rather than an open sensor, and a resistance check alone will not reveal this.
The PCM may substitute a default fuel temperature strategy when this code is active, so drivability complaints can persist even after the light clears if the underlying circuit fault remains.
Biodiesel blends and contaminated fuel can coat the sensor element and skew its low-temperature resistance, causing P1186 without any wiring fault at all.

Can I keep driving with P1186?

The vehicle is generally safe to drive short distances because the PCM substitutes a default fuel temperature value, but avoid heavy towing or sustained high-load operation until the fault is repaired. Prolonged driving with a low fuel temperature signal can affect injection timing and fuel economy, so schedule diagnosis promptly.

Tools that help

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Guidance is general and written for Ford vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.