P0189: The fuel temperature sensor B circuit gives an on-and-off signal
Fuel temperature sensor B circuit intermittent
Severity: Monitor
TroubleCodes.net lists a warning light, poor fuel economy and possible hard starting, so it is not usually urgent, but it can worsen.
It gets more serious if:
- Inspect soon: Inspect soon if the engine becomes hard to start or loses power.
P0189 in short
P0189 means the fuel temperature sensor B circuit is giving an intermittent signal. The computer saw the temperature jump more than it could in real life. A loose or corroded connector, damaged wiring or a failing sensor are the usual causes. It is usually fine to drive but get it checked.
The computer reads fuel temperature to adjust fuel delivery. If the reading jumps erratically, it sets P0189 as an intermittent fault.
Because it comes and goes, it can be hard to find; a shake test of the wiring can reproduce it.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Corroded or loose connector or damaged wiring
Common general cause- Why it ranks here
- TroubleCodes.net lists wiring problems and poor connections first.
- What would change this
- Rises if shaking the harness makes the reading jump. Falls if the harness is steady.
Cause 2: Failing fuel temperature sensor B
Common general cause- Why it ranks here
- A defective sensor is the next cause TroubleCodes.net gives.
- What would change this
- Rises if resistance is out of specification or erratic. Falls if it is within specification.
Cause 3: Engine computer fault (rare)
Possible — needs testing- Why it ranks here
- TroubleCodes.net calls this rare, so it is checked last.
- What would change this
- Rises only after wiring and sensor test good. Falls if either is faulty.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Look at the sensor and engine computer connectors for corrosion or water, and clean as needed.
IfCorrosion or water is present
It meansClean or repair the connector.
IfConnectors look good
It meansTest the wiring and sensor.
Step 2: With the engine running, wiggle the harness while watching fuel temperature on a scan tool.
Warning:Keep hands and clothing away from belts and fans, and avoid fuel lines under pressure.
IfThe reading jumps when the harness moves
It meansWiring or connector fault.
IfThe reading stays steady
It meansTest the sensor resistance.
Symptoms
- Check engine light
- Poor fuel economy
- Hard starting or loss of power Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine off, check that the sensor connector is fully seated and free of corrosion.
On your vehicle
We don't have reviewed vehicle-specific evidence for P0189 yet. The causes and tests above apply across vehicles.
Related codes
No curated relationships for P0189 yet.
P0189 questions
Why does P0189 come and go?
It is an intermittent fault, often a connector or wire that loses contact with vibration or heat.
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error