Power Steering Pump Motor Circuit Malfunction
What does C0155 mean?
The C0155 code means the vehicle's onboard diagnostic system has detected: Power Steering Pump Motor Circuit Malfunction. This is a critical severity code.
Common Symptoms
- Heavy steering at all speeds
- Power steering warning light on
- Whining noise from steering pump area
- No power steering assist
- Steering fluid overheating
Probable Causes (Ranked by Likelihood)
- Failed power steering pump or motor Very High
- Worn power steering pump drive belt High
- Low power steering fluid causing pump cavitation Moderate
- Power steering pump electrical circuit fault Low
Step-by-Step Diagnostic Procedure
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Check power steering fluid level and condition
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Inspect pump drive belt for wear or slipping
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Listen for pump whining or grinding noises
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Test pump output pressure with gauge
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Check electrical connections on electric-assist pumps
Frequently Asked Questions
Can low fluid damage the power steering pump?
Yes. Running a power steering pump without adequate fluid causes cavitation, which damages the internal vanes and bearings. Always maintain proper fluid level.
What causes the whining noise?
A whining noise from the power steering pump usually indicates air in the system, low fluid, or internal pump wear. The noise is typically loudest when the wheel is turned to full lock.
How long does a power steering pump last?
Most power steering pumps last 100,000 miles or more. Regular fluid changes and maintaining proper fluid level are the best ways to extend pump life.