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 is typically located in the fuel system, often in the fuel tank or on the fuel rail, and measures the temperature of the fuel. A high input suggests a short to voltage, a faulty sensor, or an issue with the wiring or connector. This can affect fuel delivery and engine performance.
1. Most Common Causes
- Faulty fuel temperature sensor (FTS) B or internal failure
- Signal circuit shorted to battery voltage (B+) or to a 5V reference circuit
- Sensor ground/return circuit open, corroded, or with excessive resistance
- Sensor connector with bent pins, moisture, or corrosion altering signal voltage
- Faulty powertrain control module (PCM) - rare case
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Hard starting or rough idle
- Poor fuel economy
- Engine hesitation or stalling
- Black smoke from exhaust (rich condition)
3. 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 voltage by disconnecting the sensor and measuring voltage at the harness connector.
Step 5: If sensor and wiring are okay, test the ECM's ability to read the sensor signal; replace ECM if necessary.
4. 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.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the vehicle and whether the sensor or wiring needs replacement.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.