Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2017 Subaru Forester 2.0XT PremiumFACTORY OEM SERVICE PROCEDURE
Keyless Access System
KEYLESS ACCESS SYSTEM DIAGNOSTIC TROUBLE CODE IDENTIFICATION
| DTC | Item | Content of diagnosis | Note |
|---|---|---|---|
| U0073 | CAN FAILURE, BUS 'OFF' DETECTION | Detected when CAN line abnormality is detected. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0073 CM COMMUNICATION BUS OFF . |
| U0100 | LOST COMMUNICATION WITH ECM/PCM "A" | Detected when CAN data from the engine CM (ECM) does not arrive. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0100 LOST COMMUNICATION WITH ECM/PCM "A" . |
| U0101 | LOST COMMUNICATION WITH TCM | Detected when CAN data from TCM does not arrive. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0101 LOST COMMUNICATION WITH TCM . |
| U0122 | LOST COMMUNICATION WITH VEHICLE DYNAMICS CM | Detected when CAN data from VDC does not arrive. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0122 LOST COMMUNICATION WITH VEHICLE DYNAMICS CM . |
| U0140 | LOST COMMUNICATION WITH BODY CM | Detected when CAN data from BIU does not arrive. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0140 LOST COMMUNICATION WITH BODY CM . |
| U0155 | LOST COMMUNICATION WITH INSTRUMENT PANEL CLUSTER (IPC) CM | Detected when CAN data from meter does not arrive. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0155 LOST COMMUNICATION WITH INSTRUMENT PANEL CLUSTER (IPC) CM . |
| U0401 | INVALID DATA RECEIVED FROM ECM/PCM "A" | Detected when there is malfunction in CAN data from the engine CM (ECM). | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0401 INVALID DATA RECEIVED FROM ECM/PCM "A" . |
| U0422 | INVALID DATA RECEIVED FROM BODY CM | Detected when CAN data from BIU is abnormal. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC U0422 INVALID DATA RECEIVED FROM BODY CM . |
| B1242 | Wireless tuner | When short circuit occurs in harness between keyless access CM and receiver. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B1242 Wireless tuner . |
| B2271 | IGN relay control circuit |
|
Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2271 IGN relay control circuit . |
| B2274 | ACC relay control circuit | When malfunction is detected in ACC relay drive circuit in the keyless access CM or external circuit. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2274 ACC relay control circuit . |
| B2275 | Engine start request control circuit |
|
Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2275 Engine start request control circuit . |
| B2276 | CC relay off signal | When input error occurs in accessory relay cut input signal of keyless access CM. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2276 ACC relay off signal . |
| B2277 | Submerging circuit | When the water-submersion detection circuit integrated into the keyless access CM detects the water submersion. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2277 Submerging circuit . |
| B2282 | Vehicle speed signal correlation | When the vehicle speed signal transmitted from the combination meter via solid line and the vehicle speed signal transmitted via CAN communication line do not match. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2282 Vehicle speed signal correlation . |
| B2283 | Vehicle speed sensor | Either of the following malfunctions is detected. (Vehicle speed sensor failure is detected.)
|
Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2283 Vehicle speed sensor . |
| B2284 | Brake signal correlation | When the brake signal transmitted via solid line and the brake signal transmitted via CAN communication line do not match. (AT model only) | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2284 Brake signal correlation . |
| B2285 | Steering lock position signal correlation | When the steering lock position signal transmitted from the steering lock CM via solid line and the steering lock position signal transmitted via LIN communication system do not match. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2285 Steering lock position signal correlation . |
| B2286 | Engine speed signal(without Auto Start Stop) | When the engine speed signal transmitted from the ECM via solid line and the engine speed signal transmitted via CAN communication line do not match. (Without Auto Start Stop) | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2286 Engine speed signal(without Auto Start Stop) . |
| B2779 | Remote control engine starter collation | When the keyless access CM does not respond to engine start even when the remote control engine starter is ON, or when there is a code mismatch. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2779 Remote control engine starter collation . |
| B2781 | Steering Lock CM control circuit |
|
Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2781 Steering Lock CM control circuit . |
| B2782 | Steering lock drive request signal correlation | When the open or short circuit in the steering lock motor power supply circuit is detected. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2782 Steering lock drive request signal correlation . |
| B2784 | Antenna circuit (Push Engine Switch) | When open or short circuit occurs in the antenna coil. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2784 Antenna circuit (Push Engine Switch) . |
| B2785 | LIN communication | When the keyless access CM detected the collation system LIN bus communication error three times in a row. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2785 LIN communication . |
| B2786 | Steering Lock CM communication | When communication between keyless access CM and steering lock CM is interrupted for a set amount of time. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2786 Steering Lock CM communication . |
| B2788 | IGN signal correlation (Steering Lock CM) | When mismatch occurs in the IG1 input of the steering lock CM for both LIN communication line input and solid line input. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2788 IGN signal correlation (Steering Lock CM) . |
| B2789 | ID Code Box communication |
|
Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2789 ID Code Box communication . |
| B278A | Push Engine Switch power supply circuit | When the power supply circuit of the push button ignition switch is shorted to ground. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B278A Push Engine Switch power supply circuit . |
| B278D | ID Code Box judgment circuit | When ID code box setting is set to OFF, ID code box LIN signal is received. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B278D ID Code Box judgment circuit . |
| B2790 | ID Code Box circuit | An error has occurred inside the ID code box. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B2790 ID Code Box circuit . |
| B27A1 | Driver side external antenna open | When open circuit occurs in the harness between keyless access CM and driver's side front door outer handle. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A1 Driver side external antenna open . |
| B27A2 | Passenger side external antenna open | When open circuit occurs in the harness between keyless access CM and passenger's side front door outer handle. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A2 Passenger side external antenna open . |
| B27A5 | Front internal antenna open | When open circuit occurs in the harness between keyless access CM and front interior antenna. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A5 Front internal antenna open . |
| B27A6 | Rear internal antenna open | When open circuit occurs in the harness between keyless access CM and rear interior antenna. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A6 Rear internal antenna open . |
| B27A7 | Trunk/rear gate internal antenna open | When open circuit occurs in the harness between keyless access CM and rear interior antenna. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A7 Trunk/rear gate internal antenna open . |
| B27A8 | Trunk/rear gate external antenna open | When open circuit occurs in the harness between keyless access CM and rear exterior antenna. | Ref. to KEYLESS ACCESS WITH PUSH BUTTON START (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC B27A8 Trunk/rear gate external antenna open . |
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.