OBD Guide
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C1166

Suction Valve 1

C1166 is an OBD-II diagnostic trouble code meaning: Suction Valve 1. Common causes: faulty solenoid suction valve coil, open or short circuit in valve control circuit. Estimated repair cost: $11–556.

Severity
🔴 High
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$11–556 (est.)

Symptoms

  • The ABS and/or ESP indicator on the dashboard is on
  • ABS system does not work during emergency braking
  • Brake pedal pulsation during normal braking
  • Diagnostic code C1166
  • Increased braking distance during emergency braking

Causes

  • Faulty solenoid suction valve coil
  • Open or short circuit in valve control circuit
  • Valve clogged with contaminated brake fluid
  • Malfunction of the ABS/ESP control unit
  • Damage to the ABS hydraulic unit

How to Fix

  1. Connect a diagnostic scanner and read ABS error codes
  2. Check the supply voltage and control signal at the ABS hydraulic unit connector
  3. Check the resistance of the suction valve winding (usually 2-5 ohms) with a multimeter
  4. Measure the condition of the brake fluid - if it is heavily contaminated, perform a complete replacement
  5. If a valve malfunction is detected, replace the ABS hydraulic unit (valves are usually not repaired separately)
  6. After repair, bleed the brake system and check ABS operation

Related codes

C1200C12B6C1356C1368C1252

FAQ

What does the C1166 code mean?

C1166 is an OBD-II diagnostic trouble code that indicates: Suction Valve 1

What causes a C1166 error code?

The most common causes of C1166 include: Faulty solenoid suction valve coil; Open or short circuit in valve control circuit; Valve clogged with contaminated brake fluid; Malfunction of the ABS/ESP control unit.

How do I fix a C1166 diagnostic trouble code?

To fix C1166: Connect a diagnostic scanner and read ABS error codes. Check the supply voltage and control signal at the ABS hydraulic unit connector. Check the resistance of the suction valve winding (usually 2-5 ohms) with a multimeter. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with C1166?

Yes, but get it checked soon

How much does it cost to fix C1166?

The estimated repair cost for C1166 is $11–556. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat