Engine Coolant Level Sensor Circuit High
The P2558 code means the vehicle's onboard diagnostic system has detected: Engine Coolant Level Sensor Circuit High. This is a moderate severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- easy
- Estimated cost
- $50 - $200 (parts and labor)
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Common Symptoms
- No low coolant warning even when coolant is low
- Check engine light on
- Coolant gauge reads full constantly
- Risk of overheating without warning
Probable Causes (Ranked by Likelihood)
- Sensor signal wire shorted to reference voltage Very High
- Coolant level sensor stuck in high position High
- Open ground wire causing high signal Moderate
- ECM input circuit fault Low
Step-by-Step Diagnostic Procedure
-
Lower coolant level and verify sensor responds
-
Check sensor signal for constant high voltage
-
Test sensor ground circuit for continuity
-
Inspect sensor float for mechanical binding
Frequently Asked Questions
Is P2558 more dangerous than P2557?
Potentially yes. P2558 means the sensor always reads full, so you will not receive a warning if coolant actually drops to a dangerous level, risking overheating.
How can I monitor coolant without the sensor?
Regularly check the coolant reservoir visually. The level should be between the minimum and maximum marks when the engine is cold.
Can a stuck float cause P2558?
Yes. If the float mechanism in the sensor is stuck in the up position from debris or scale buildup, it will always indicate a full coolant level.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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