P1191 Fuel Pump Temp Sensor Low Voltage
The P1191 code indicates that the engine control module (ECM) has detected a voltage signal from the fuel pump temperature sensor (FTS) that is below the expected range. This sensor monitors the temperature of the fuel pump module to prevent overheating and fuel vaporization. A low signal typically points to an open circuit, a short to ground, or excessive resistance in the sensor wiring. On Hyundai/Kia vehicles, this code is directly linked to the fuel management system and may trigger engine protection modes.
01. Most Common Causes
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Possible reduced engine performance or limp mode
03. Step-by-Step Diagnosis
Scan for codes and verify P1191 is present
Inspect the fuel pump temperature sensor connector for corrosion, damage, or loose pins
Measure sensor resistance and compare to manufacturer specifications
Check for shorts to ground or opens in the wiring between sensor and ECM
If wiring and sensor check out, test the fuel pump assembly for internal faults
As a last resort, evaluate ECM for rare failure
1. Frequently Asked Questions
Is it safe to drive?▼
It is moderately safe for short trips, but continued driving may lead to fuel pump overheating or reduced performance. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $500, depending on whether the sensor, wiring, or fuel pump assembly needs replacement.