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U0104 on Subaru Ascent

Lost Communication with Cruise Control Module

Factory diagnostic protocol and troubleshooting wire for fault code U0104 specifically for the Subaru Ascent (2020–2026, 2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque)).

Verified OEM Telemetry & Field Repair Tree
Subaru Ascent2020–2026
Subaru Ascent
SUV2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Ascent SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Not Recommended
Low urgency level
Est. Repair Cost
$100 - $450 (DIY: $0 - $150)
Parts & Labor DIY
Check U0104 On Another Subaru Model:
Diagnose U0104 on Specific Ascent Model Year:

1. Symptoms of U0104 on Subaru Ascent

When the Engine Control Module (ECM/PCM) on your Subaru Ascent (2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque)) logs fault code U0104, drivers commonly observe:

Adaptive Cruise Control (ACC) disabled on Subaru Ascent (2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque))
Pre-Collision System warning light on on Subaru Ascent (2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque))
Check Engine Light on on Subaru Ascent (2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque))
Subaru Ascent OBD-II Port Location
The 16-pin diagnostic connector is located Lower driver kick panel near hood lever. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Subaru Ascent

Historical warranty claims and technical repair bulletins for Subaru Ascent point to the following failure distribution:

55%
Blocked or dirty front radar sensor in grille/bumper (Subaru OEM Part)
25%
Blown radar module fuse (Subaru OEM Part)
12%
Faulty radar cruise control module (Subaru OEM Part)
8%
Misaligned radar sensor following minor bumper bump (Subaru OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Subaru Ascent.

3. Step-by-Step DIY Repair Guide for Subaru Ascent

01
Clean Front Radar Sensor in Grille

Clean snow, ice, mud, or dead bugs off front radar emblem. on the Subaru Ascent equipped with 2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque).

Required Tool: Microfiber Towel
02
Check ACC / Radar Fuse

Verify power feed to radar sensor. on the Subaru Ascent equipped with 2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque).

Required Tool: Test Light
03
Perform Radar Aiming Calibration

Execute optical/radar alignment procedure if bumper was removed. on the Subaru Ascent equipped with 2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque).

Required Tool: Calibration Target, Scan Tool
04
Clear Trouble Codes

Clear DTCs and test cruise on highway. on the Subaru Ascent equipped with 2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque).

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing Subaru Ascent (U0104)

Prime Fast Delivery & Verified Fitment
Direct-Fit Replacement Part

Subaru Ascent OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

Direct-fit replacement assembly engineered to OEM tolerances for Subaru Ascent.

$45 – $95 Prime
Check Fitment on Amazon
Sensor Signal Voltage Meter

AstroAI Auto-Ranging Digital Multimeter

4.6 / 5.0 (Best Seller)

Essential for testing 0.1V–5.0V sensor reference signals, ground continuity (<0.20Ω), and harness resistance.

$29.99 Prime
View on Amazon
Top Mobile OBD-II Scanner

BlueDriver Bluetooth Pro OBDII Scan Tool

4.7 / 5.0 (50,000+ Reviews)

Reads and clears enhanced codes (ABS, Airbag, Transmission, Engine) & live freeze-frame telemetry on phone.

Compare OEM & Aftermarket Replacement Sensors for Subaru AscentVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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Other Common Fault Codes on Subaru Ascent

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Subaru Ascent:

4. Subaru Ascent U0104 FAQs

What causes code U0104 to trigger on a Subaru Ascent?

On the Subaru Ascent (2.4L Turbocharged DOHC Boxer-4 (260HP / 277 lb-ft torque)), U0104 is most frequently caused by Blocked or dirty front radar sensor in grille/bumper or Blown radar module fuse.

Where is the OBD-II port located on my Subaru Ascent?

On the Subaru Ascent, the 16-pin DLC diagnostic connector is located Lower driver kick panel near hood lever. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Subaru Ascent with code U0104?

Yes. Normal driving is unaffected, but Adaptive Cruise Control will not engage. Given that U0104 carries a Low severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.