Fuel Temperature Sensor B Circuit Intermittent/Erratic
The P0189 code means the vehicle's onboard diagnostic system has detected: Fuel Temperature Sensor B Circuit Intermittent/Erratic. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- moderate
- Estimated cost
- $60 - $300 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Erratic fuel temperature readings
- Possible driveability issues during temperature reading spikes
- Inconsistent fuel economy
Probable Causes (Ranked by Likelihood)
- Degraded fuel temperature sensor B with erratic output Very High
- Corroded wiring causing resistance changes High
- EMI interference on sensor signal wire Moderate
- PCM analog-to-digital converter issue Low
Step-by-Step Diagnostic Procedure
-
Monitor sensor B readings on scan tool for erratic spikes or drops that do not correlate with engine temperature changes.
-
Inspect wiring for corrosion, especially at connectors and splice points.
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Check wiring routing for proximity to high-current or high-voltage lines that could cause interference.
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Replace sensor if wiring tests clean and readings remain erratic.
Frequently Asked Questions
What is the difference between P0188 and P0189?
P0188 indicates an intermittent dropout (the signal drops out briefly), while P0189 indicates erratic or noisy readings that vary unpredictably.
Can electrical interference cause P0189?
Yes, if the sensor signal wire runs too close to injector wires, alternator output, or other high-current sources, interference can corrupt the signal.
How do I fix erratic sensor readings?
Start by replacing the sensor. If the problem persists, inspect wiring for corrosion and check routing to avoid high-current wire bundles.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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