P1191 — FTS Low - Fuel Pump Temperature Sensor Low

Meaning for brands

Dongfeng

For Ford vehicles

TP controlled circuit Mazda or 02 sensor heater hardware foult Jaguar or key line voltage diesel – open circuit

powertrain (engine/transmission)

Is it safe to drive?

Drive with caution Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P1191 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the fuel delivery and mixture control for damage, corrosion, chafing or poor contact.
Subsystem check Measure fuel pressure at the rail and compare with factory specification at idle and under load.
Subsystem check Check short-term and long-term fuel trims in live data to see which way the mixture is off.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P1191 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P1191 (parts and labor, USD, independent shop rates): Replace the pressure regulator or sensor: $150–$450; Replace the fuel filter: $80–$200; Replace the fuel pump: $400–$900; Clean or replace injectors: $200–$800. Overall, fixing P1191 usually costs between $80 and $900. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What is the most common cause of P1191?

The most common causes are: faulty fuel pressure regulator, faulty fuel rail pressure sensor or wiring, clogged or leaking fuel injectors.

How much does it cost to fix P1191?

Replace the pressure regulator or sensor — $150–$450; Replace the fuel filter — $80–$200; Replace the fuel pump — $400–$900; Clean or replace injectors — $200–$800. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Will P1191 clear itself?

Sometimes P1191 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What are the symptoms of P1191?

Drivers most often notice: rough idle and hesitation, fuel smell in severe cases, loss of power under load, increased fuel consumption.

Is it safe to drive with P1191?

Drive with caution. Mixture and fuel-pressure faults can cause stalling, hesitation in traffic and — when severe — catalyst damage. Avoid long trips until diagnosed.

The engine control module logs code P1191 when it recognizes that the fuel pump temperature sensor is reporting an abnormally low voltage signal. This sensor monitors fuel temperature inside the pump module, and the ECU relies on this reading to adjust fuel delivery for proper combustion. When the reported value falls below the expected range, the module triggers P1191 and illuminates the Check Engine light.

The fuel delivery and mixture control system works as a closed loop. The ECU compares inputs from multiple sensors—including the fuel pump temperature sensor, manifold absolute pressure sensor, and oxygen sensors—to calculate the correct fuel injector pulse width. If the temperature sensor feeds the module bad data, the entire fuel mixture calculation becomes skewed. P1191 does not set on a single bad reading alone. The module must observe the low-temperature fault condition repeat under specific operating parameters—typically engine RPM, load, and temperature ranges—before it records the trouble code and stores freeze frame data describing exactly when the failure occurred.

Understanding this two-trip fault logic matters for diagnosis. The freeze frame snapshot captures engine load, RPM, coolant temperature, vehicle speed, and other key values at the moment P1191 was set. That data points you toward the exact driving conditions that triggered the code, which is where you should focus your testing.

Common Symptoms of P1191

Rough idle and hesitation during acceleration
Noticeable fuel odor, especially in more severe cases
Reduced engine power when under load
Fuel economy noticeably worse than normal
Extended cranking time or difficulty starting the engine
Check Engine light illuminated on the dashboard

Common Causes

The most frequent culprits behind P1191 involve anything that disrupts the fuel delivery system or sends incorrect signals to the ECU:

Intake or vacuum leaks that throw off the air-fuel mixture calculation
Faulty fuel rail pressure sensor or damaged associated wiring
Malfunctioning fuel pressure regulator
Weakened fuel pump or restricted fuel filter
Clogged or leaking fuel injectors affecting mixture delivery

How to Diagnose P1191

Follow a logical sequence to pinpoint the root cause without replacing parts unnecessarily:

Connect an OBD2 scanner and confirm P1191 is stored in the ECU memory. Save the freeze frame data immediately—it documents engine load, RPM, coolant temperature, and speed at the moment the fault triggered. These values guide your testing conditions.
Search for related diagnostic trouble codes stored alongside P1191. Accompanying codes often reveal the actual failing component. Check manufacturer technical service bulletins for your specific make and model through the manufacturer website or nhtsa.gov—many P0xxx codes have documented factory fixes or calibration updates.
Perform a thorough visual inspection of the wiring harness and electrical connectors in the fuel delivery circuit. Look for damaged insulation, corrosion at the pins, chafing from contact with other components, or loose connections that could interrupt the sensor signal.
Measure fuel pressure at the fuel rail and compare the results against factory specifications. Test at idle and again under simulated load conditions to see whether pressure holds steady or drops abnormally.
Monitor short-term and long-term fuel trim values in live data mode. Positive trims indicate the ECU is adding extra fuel to compensate for a lean condition, while negative trims suggest it is pulling fuel to correct a rich condition—both point toward mixture-related faults.
Clear the code and complete a full drive cycle that reproduces the freeze frame conditions. If P1191 returns, the fault is confirmed and still present.

Repair Options and Costs

Address the cheapest and most likely causes first before spending money on major components:

Replace the fuel pressure regulator or fuel rail pressure sensor: $150–$450
Replace the fuel filter: $80–$200
Replace the fuel pump: $400–$900
Clean or replace fuel injectors: $200–$800

The total repair bill for P1191 typically falls between $80 and $900 depending on which component failed. An accurate diagnosis before purchasing parts prevents unnecessary spending—the worst-case scenario involving a new fuel pump is rarely the first thing to check.

Can You Drive with P1191?

Drive with caution. Faults in the fuel mixture and pressure system can lead to stalling, hesitation during traffic merges, and rough engine performance. In severe cases, a consistently lean fuel mixture can overheat and damage the catalytic converter. Avoid long highway trips until the underlying cause is identified and corrected.