U0104 on Subaru: Symptoms, Causes & Fix
Official technical diagnostic wire for fault code U0104 specifically affecting Subaru vehicles (Outback, Forester, Crosstrek, WRX, Ascent).
Select Your Subaru Model for U0104:
1. Common Symptoms on Subaru Vehicles
When Subaru Engine Control Modules (ECM) trigger fault code U0104, drivers typically report:
2. Root Causes on Subaru Engines
Historical diagnostic claims across Subaru engines point to the following failure distribution:
3. Step-by-Step Fix Protocol for Subaru
Clean snow, ice, mud, or dead bugs off front radar emblem. on Subaru engines.
Verify power feed to radar sensor. on Subaru engines.
Execute optical/radar alignment procedure if bumper was removed. on Subaru engines.
Clear DTCs and test cruise on highway. on Subaru engines.
Equipment for Diagnosing Subaru (U0104)
Subaru OEM Replacement Sensor
Direct-fit replacement assembly engineered to OEM tolerances for Subaru.
AstroAI Auto-Ranging Digital Multimeter
Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.
BlueDriver Bluetooth Pro OBDII Scan Tool
Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.
4. Subaru U0104 Frequently Asked Questions
What does code U0104 mean on a Subaru?
On Subaru vehicles, U0104 indicates that the Engine Control Module (ECM) detected lost communication with cruise control module. This typically points to Blocked or dirty front radar sensor in grille/bumper or Blown radar module fuse.
Can I continue driving my Subaru with code U0104?
Yes. Normal driving is unaffected, but Adaptive Cruise Control will not engage. Because this code carries a Low severity rating on Subaru powertrains, we recommend scanning live data values promptly to prevent secondary damage.
How much does it cost to fix code U0104 on a Subaru?
Estimated DIY parts cost ranges from $100 - $450 (DIY: $0 - $150), while professional shop repairs at an authorized Subaru dealership or independent specialist typically range from $180 to $380 including diagnostic labor.