What Does P0189 Mean?
The fuel temperature sensor B is providing an intermittent signal, with the ECM detecting momentary dropouts, spikes, or erratic readings that fall outside normal sensor behavior. This is an electrical reliability issue rather than a consistent failure. The driver may notice brief, occasional engine hesitation or slight fuel economy variations.
Common Causes
35%
Loose or corroded fuel temperature sensor B connector causing intermittent contact
25%
Chafed or damaged wiring that intermittently shorts or opens under vibration
20%
Internally failing fuel temperature sensor B with thermal-sensitive intermittent fault
12%
Poor ground connection with intermittent high resistance
8%
ECM connector pin fatigue or micro-fracture
Diagnostic Steps
1
Monitor the fuel temperature sensor B PID in live data and perform a wiggle test — gently move the connector and wiring while watching for sudden value changes or signal dropouts.
2
Inspect the sensor connector for corrosion, spread terminals, or evidence of moisture intrusion. Clean with electrical contact cleaner and apply dielectric grease.
3
Back-probe the sensor signal at the ECM and sensor connectors simultaneously to isolate whether the intermittent fault is at the sensor, wiring, or ECM end.
4
Check the wiring harness routing for areas where it contacts moving parts, hot surfaces, or sharp edges that could cause intermittent insulation breakdown.
5
Measure sensor resistance while heating/cooling it with a heat gun — resistance should change smoothly with no sudden jumps. Erratic behavior confirms internal sensor failure.
Estimated Repair Cost
$50 - $250
Parts + labor, varies by vehicle and location
The fuel temperature sensor B is providing an intermittent signal, with the ECM detecting momentary dropouts, spikes, or erratic readings that fall outside normal sensor behavior. This is an electrical reliability issue rather than a consistent failure. The driver may notice brief, occasional engine...
The most common cause of P0189 (Fuel Temperature Sensor B Circuit Intermittent) is: Loose or corroded fuel temperature sensor B connector causing intermittent contact
Typical repair costs for P0189 range from $50 to $250, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. Intermittent fuel temperature data has minimal impact on engine operation. The ECM compensates well with substitute values. No safety concern; repair when convenient.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0189 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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