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Subaru B22A5

If B2A20 is found in combination with U1F0188, B22A4, or B22A5, do not ignore them. Proceed with the specific trouble-tree diagnosis for those secondary codes identified in STIS. A

DriveUnknown. The supplied verified evidence does not establish whether the vehicle is safe to drive with B22A5.
ChargeUnknown. The supplied verified evidence does not establish whether the vehicle is safe to charge with B22A5.
ServiceService evaluation is appropriate when B22A5 is detected with B2A20, because Subaru's documented instruction is to proceed with the specific STIS trouble-tree diagnosis for the secondary code.
Confidence95%

Quick answer

For Subaru vehicles listed below, B22A5 is identified in official manufacturer communications as a secondary code that must not be ignored when it is present with B2A20. The documented direction is to use the specific STIS trouble-tree diagnosis for B22A5.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does B22A5 mean?

For Subaru vehicles listed below, B22A5 is identified in official manufacturer communications as a secondary code that must not be ignored when it is present with B2A20. The documented direction is to use the specific STIS trouble-tree diagnosis for B22A5.

2. Technical explanation

Verified Subaru service communication evidence states that when B2A20 is found together with U1F0188, B22A4, or B22A5, the secondary code must not be ignored. For B22A5, the documented diagnostic direction is to proceed with the specific trouble-tree diagnosis identified in STIS. The supplied evidence does not establish a component-level definition, fault mechanism, or repair for B22A5 alone.

3. What system is affected?

Not yet established by verified evidence.

4. How serious is this code?

Unknown. The supplied verified evidence does not assign a severity level.

5. Symptoms you may notice

  • Not yet established by verified evidence.

6. Possible causes

  • Not yet established by verified evidence.

7. Can I still drive the vehicle?

Unknown. The supplied verified evidence does not establish whether the vehicle is safe to drive with B22A5.

8. Can I charge the vehicle?

Unknown. The supplied verified evidence does not establish whether the vehicle is safe to charge with B22A5.

9. What you can safely do

  • Record all diagnostic trouble codes present rather than focusing only on B2A20.
  • If B22A5 is present with B2A20, have the B22A5-specific STIS trouble-tree diagnosis performed by an appropriately qualified Subaru service provider.
  • Do not disregard B22A5 when it appears as a secondary code with B2A20.

10. Step-by-step troubleshooting

  1. Confirm whether B22A5 is stored together with B2A20.
  2. If B2A20 and B22A5 are both present, follow the B22A5-specific trouble-tree diagnosis in Subaru STIS.
  3. The supplied evidence does not establish additional user-performed diagnostic steps.

11. When to contact service

Service evaluation is appropriate when B22A5 is detected with B2A20, because Subaru's documented instruction is to proceed with the specific STIS trouble-tree diagnosis for the secondary code.

12. What the service center may check

  • Retrieve and document all stored DTCs.
  • Determine whether B2A20 is present in combination with B22A5.
  • Perform the B22A5-specific diagnostic trouble tree in Subaru STIS when the documented code combination is present.

13. Possible repair or resolution

  • Not yet established by verified evidence. The supplied communications direct diagnosis through the applicable STIS trouble tree but do not specify a repair.

14. Affected vehicles

15. Related TSBs / service bulletins

  • NHTSA Manufacturer Communication PDF 11032034: 07-240-26R, published April 30, 2026. It states that when B2A20 is found with U1F0188, B22A4, or B22A5, the secondary codes should not be ignored and the specific STIS trouble-tree diagnosis should be used.
  • NHTSA Manufacturer Communication PDF 11029347: 07-240-26R, published February 25, 2026. It provides the same documented direction regarding B2A20 combined with U1F0188, B22A4, or B22A5.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official source: NHTSA-hosted Subaru manufacturer communications 07-240-26R: https://static.nhtsa.gov/odi/tsbs/2026/MC-11032034-0001.pdf and https://static.nhtsa.gov/odi/tsbs/2026/MC-11029347-0001.pdf

19. Frequently asked questions

What does Subaru documentation say to do when B22A5 is present with B2A20?

Do not ignore B22A5. Proceed with the specific trouble-tree diagnosis for the secondary code in Subaru STIS.

Does the supplied evidence identify the failed part for B22A5?

No. A component-level cause is not yet established by verified evidence.

Is B22A5 by itself proven to make the vehicle unsafe to drive or charge?

No. Drive safety and charging safety are not yet established by verified evidence.

20. Sources & verification

Verified
Subaru B22A5: If B2A20 is found in combination with U1F0188, B22A4, or… | EV Diagnostics