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U0073 on Subaru Forester

Control Module Communication Bus A Off

Factory diagnostic protocol and troubleshooting wire for fault code U0073 specifically for the Subaru Forester (2020–2026, 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD)).

Verified OEM Telemetry & Field Repair Tree
Subaru Forester2020–2026
Subaru Forester
SUV2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD)
Reliability
Sensor Voltage Ref
0.1V – 5.0V Ref
Forester SAE Mode $01
ECU Network Bus
500 kbps CAN-FD
ISO 15765-4 Compliant
Drivability Status
Not Recommended
Critical urgency level
Est. Repair Cost
$150 - $850 (DIY: $40 - $200)
Parts & Labor DIY
Check U0073 On Another Subaru Model:
Diagnose U0073 on Specific Forester Model Year:

1. Symptoms of U0073 on Subaru Forester

When the Engine Control Module (ECM/PCM) on your Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD)) logs fault code U0073, drivers commonly observe:

StabiliTrak / Traction / ABS / Engine warning lights lit on Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD))
Transmission shifting harshly or refusing to shift out of 2nd gear on Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD))
No communication with TCM, ABS, or BCM on Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD))
Engine may refuse to crank on Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD))
Subaru Forester OBD-II Port Location
The 16-pin diagnostic connector is located Driver lower dash panel near hood lever. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Subaru Forester

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

55%
Loose or corroded ground connection on transmission or frame (Subaru OEM Part)
25%
Faulty Transmission Control Module (TCM) or ABS module pulling bus down (Subaru OEM Part)
12%
Poor connection at large body-to-chassis pass-through harness connector (Subaru OEM Part)
8%
Aftermarket accessory (remote starter, GPS tracker, cheap OBD scanner) broadcasting invalid data (Subaru OEM Part)
* Source: Synthesized from NHTSA ODI field repair telemetry and verified OEM Technical Service Bulletin (TSB) repair tree frequency percentiles for Subaru Forester.

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

01
Unplug All Aftermarket OBD-II Devices

Remove any aftermarket insurance dongles, GPS trackers, or scan tools plugged into the DLC port. on the Subaru Forester equipped with 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD).

Required Tool: None
02
Inspect Frame and Transmission Ground Straps

Inspect braided ground straps on engine and transmission. Clean all contact surfaces to bare metal. on the Subaru Forester equipped with 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD).

Required Tool: Wire Brush, Sockets
03
Perform Full Vehicle Network Topology Scan

Scan all modules on vehicle. Note which modules are online and which are offline to pinpoint the break in the network daisy-chain. on the Subaru Forester equipped with 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD).

Required Tool: Full-System OBD-II Diagnostic Scanner
04
Check Terminating Resistance (60 Ohms)

Verify 60 ohms across Pins 6 and 14 with battery disconnected. on the Subaru Forester equipped with 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD).

Required Tool: Multimeter
05
Clear All System DTCs & Road Test

Clear DTCs from all modules and road test to verify error-free network transmission. on the Subaru Forester equipped with 2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD).

Required Tool: Scan Tool
Recommended Parts & Testing Tools

Equipment for Diagnosing Subaru Forester (U0073)

Prime Fast Delivery & Verified Fitment
Direct-Fit Replacement Part

Subaru Forester OEM Replacement Sensor

4.7 / 5.0 (Verified Fit)

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

$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 ForesterVerified direct-fit pricing from Denso, Bosch, Motorcraft, and ACDelco on Amazon.
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Other Common Fault Codes on Subaru Forester

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

4. Subaru Forester U0073 FAQs

What causes code U0073 to trigger on a Subaru Forester?

On the Subaru Forester (2.5L Direct Injection Boxer-4 (182HP / Symmetrical AWD)), U0073 is most frequently caused by Loose or corroded ground connection on transmission or frame or Faulty Transmission Control Module (TCM) or ABS module pulling bus down.

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

On the Subaru Forester, the 16-pin DLC diagnostic connector is located Driver lower dash 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 Forester with code U0073?

No. Bus is shut down due to excessive transmission errors, leaving vehicle in unpredictable limp mode. Given that U0073 carries a Critical severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.