Fuel Temperature Sensor B Circuit High Input
The P0188 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the fuel temperature sensor B that is higher than the expected range. This sensor monitors the temperature of the fuel in the fuel rail or return line, and a high input typically means the sensor is reading an abnormally high voltage, which could be due to a short to power, a faulty sensor, or wiring issues. This can lead to incorrect fuel delivery calculations, affecting engine performance and emissions.
01. Most Common Causes
- Faulty fuel temperature sensor B
- Short to power in the sensor circuit
- Open or shorted wiring or connector issues
- Corroded or damaged sensor connector
- Faulty ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Hard starting, especially when hot
- Black smoke from exhaust (rich mixture)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the fuel temperature sensor B and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance and voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check for a short to power by disconnecting the sensor and measuring voltage at the harness connector.
Step 5: If sensor and wiring are okay, test the ECM's input circuit; replace ECM if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can cause poor engine performance, reduced fuel economy, and potential damage to the catalytic converter due to incorrect air-fuel mixture.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause. A sensor replacement is usually around $50-$100, while wiring repairs may cost more.