C0090

Code

OPEL C — Chassis

Rear Right Inlet Solenoid Valve Circuit Malfunction

Brand: OPEL

Type: C — Chassis

Views: UK: 5 EN: 6 RU: 6

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Page language: EN

Causes

Broken or frayed wiring in the solenoid harness
Corroded or loose connector at the hydraulic unit or chassis ground
Open or shorted solenoid coil (valve) inside the ABS modulator
Faulty ABS/ESP control module output driver
Contamination or water ingress in the hydraulic block causing intermittent contact
Blown fuse or poor power/ground supply to the ABS module

Symptoms

ABS and/or ESP warning lamp illuminated on the dashboard
Possible traction control lamp or stability control failure
Loss of ABS modulation at rear-right wheel; longer stopping distances under ABS events
Unusual brake pedal feel during ABS activation (pulsing or reduced modulation)
Diagnostic trouble codes stored in the ABS/ESP control unit

What to check

Read and record all stored ABS/ESP codes and freeze-frame data with a capable scan tool
Inspect harness and connector at the ABS hydraulic unit for corrosion, bent pins, water intrusion or damage
Check ABS fuses and battery connections for proper power and ground
Perform wiggle test on wiring while monitoring live data or fault status for intermittent faults
Measure solenoid coil resistance and compare to specification
Command/activate the solenoid with a diagnostic tool (actuator test) and monitor voltage/current

Signal parameters

Coil resistance: typically low (single to tens of ohms); consult OEM spec for exact value
Activation signal: switched 12 V or PWM from ABS module; voltage present when commanded
Expected behavior during actuator test: module supplies pulses and current increases when solenoid commanded
Open circuit: infinite resistance or no current draw when energized
Short/high current: very low resistance and excessive current draw; may trip module protections

Diagnostic algorithm

Safety: Park vehicle, chock wheels, disable ignition and follow manufacturer safety procedures for working near the brake system and ABS unit.
Read Codes: Use a full-function scan tool to read stored/active codes and live data. Note freeze frame and clear codes to retest.
Visual: Inspect the ABS hydraulic unit connector, harness routing to the rear-right solenoid, and chassis grounds for damage or corrosion.
Resistance: Disconnect solenoid connector and measure coil resistance at the connector pins. Compare with OEM spec (open = fault; very low = short).
Continuity/Shorts: Check continuity from the solenoid connector to the ABS module connector pins; check for shorts to battery positive and to chassis ground.
Power/Activation: With a fused jumper or diagnostic tool, command the solenoid while monitoring voltage at the connector. Confirm module is issuing the activation signal.
Swap/Compare: If possible, compare with the corresponding inlet solenoid on another channel (e.g., swap connectors or solenoids) to determine if problem follows the harness or the module.
Inspect Hydraulic Block: If wiring and solenoid appear OK, inspect hydraulic block for corrosion or internal valve faults; replace solenoid cartridge if removable.
Module Check: If wiring and solenoid are good but circuit fault persists, investigate ABS module driver outputs; consider bench testing or replacement per OEM guidance.
Repair & Verify: Repair wiring/connector or replace solenoid/module as required. Clear codes, perform drive test and actuator tests to confirm fault is resolved.

Likely causes

Damaged connector at the rear-right solenoid (corrosion from moisture)
High resistance in wiring from chafing or pinched harness
Failed solenoid coil (open or partial short)
Faulty module driver stage (internal to ABS control unit)
Loose or corroded ground or battery connection affecting module operation

Fault status

⚠️ Status

C0090 — Rear Right Inlet Solenoid Valve Circuit Malfunction: electrical fault in rear-right inlet solenoid circuit (open/short/high resistance/intermittent). ABS/ESP modulation for that wheel may be disabled.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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