What Does P0188 Mean?
The fuel temperature sensor B circuit is sending a higher voltage signal than the ECM expects, indicating an abnormally high perceived fuel temperature or an open circuit condition. This causes the ECM to miscalculate fuel density, potentially leading to slightly lean or rich fuel delivery. The driver may notice minor driveability issues or reduced fuel economy.
Common Causes
30%
Open circuit in the fuel temperature sensor B signal or ground wire
30%
Fuel temperature sensor B has failed open (infinite resistance)
20%
Corroded or disconnected sensor connector
12%
Damaged sensor ground path causing high resistance
8%
ECM connector pin back-out or internal pull-up failure
Diagnostic Steps
1
Check the fuel temperature sensor B PID — if reading maximum temperature (e.g., 280°F+) the circuit is likely open.
2
Inspect the sensor connector for full engagement, backed-out pins, or corrosion. Verify the terminal lock tab is holding the connector securely.
3
Measure sensor resistance at the sensor connector (unplug first). An open-circuit reading (OL/infinite) at room temperature confirms a failed sensor.
4
If sensor resistance is within spec, check continuity of the signal wire and ground wire from the sensor connector to the ECM connector — resistance should be under 2 Ω for each wire.
5
Verify the sensor ground by measuring resistance from the sensor ground pin to battery negative — should be under 0.5 Ω.
Estimated Repair Cost
$40 - $200
Parts + labor, varies by vehicle and location
The fuel temperature sensor B circuit is sending a higher voltage signal than the ECM expects, indicating an abnormally high perceived fuel temperature or an open circuit condition. This causes the ECM to miscalculate fuel density, potentially leading to slightly lean or rich fuel delivery. The driv...
The most common cause of P0188 (Fuel Temperature Sensor B Circuit High Input) is: Open circuit in the fuel temperature sensor B signal or ground wire
Typical repair costs for P0188 range from $40 to $200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving. The ECM will substitute a default fuel temperature for calculations. Fuel economy may be slightly affected. No safety risk; repair at your convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0188 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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