EV Diagnostics
Verified EV diagnostic knowledge page

Volvo U029A00

*Update vehicle software as per TJ 31543, then

DriveUnknown. The supplied evidence does not establish whether the vehicle is safe to drive with U029A00.
ChargeUnknown. The supplied evidence does not establish whether the vehicle is safe to charge with U029A00.
ServiceService is appropriate because the verified Volvo guidance is a BECM software product update. The evidence does not establish urgency or driving/charging status, so a service provider should assess the vehicle’s current warnings, diagnostic results, and software applicability.
Confidence95%

Quick answer

For certain US-market 2016–2019 Volvo XC90 and 2017–2019 S90/XC60 vehicles, DTC U029A00 is identified in Volvo Technical Journal (TJ) 33931 as “Lost Communication with Sensor Module.” The verified service direction is a Battery Energy Control Module (BECM) software update, with one version directing that vehicle software be updated per TJ 31543 first.

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

Video guides

Watch Videos

Relevant videos play here without leaving this diagnostic page.

No sufficiently relevant embeddable video has been accepted for this diagnostic yet.

Videos are supporting material and never override OEM or regulator evidence.

1. What does U029A00 mean?

For certain US-market 2016–2019 Volvo XC90 and 2017–2019 S90/XC60 vehicles, DTC U029A00 is identified in Volvo Technical Journal (TJ) 33931 as “Lost Communication with Sensor Module.” The verified service direction is a Battery Energy Control Module (BECM) software update, with one version directing that vehicle software be updated per TJ 31543 first.

2. Technical explanation

NHTSA-published Volvo manufacturer communications for TJ 33931 state that updated BECM software is available through a Software Product and that it addresses U029A00. The journal lists U029A00 as an intermittent BECM DTC. The provided evidence does not establish a component-level failure cause for an individual vehicle.

3. What system is affected?

Battery Energy Control Module (BECM), based on the TJ 33931 DTC listing.

4. How serious is this code?

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

5. Symptoms you may notice

  • U029A00 may be stored as an intermittent BECM DTC.
  • TJ 33931 also references no, reduced, or incorrect onboard-charger function; warnings or text windows while driving; and other problems. The supplied evidence does not establish that each symptom will occur with U029A00 alone.
  • TJ 33931 states that irregular or low electrical distance shown in the driver information module is among the issues addressed by the BECM software update.

6. Possible causes

  • A vehicle software/BECM software condition is addressed by the software product described in Volvo TJ 33931.
  • A specific root cause beyond the software-update direction is not yet established by verified evidence.

7. Can I still drive the vehicle?

Unknown. The supplied evidence does not establish whether the vehicle is safe to drive with U029A00.

8. Can I charge the vehicle?

Unknown. The supplied evidence does not establish whether the vehicle is safe to charge with U029A00.

9. What you can safely do

  • Arrange diagnosis with an authorized Volvo retailer or qualified service provider.
  • Provide DTC U029A00 and ask the service provider to check applicability of Volvo TJ 33931 and the current online version of the journal.
  • Do not attempt high-voltage battery, sensor-module, or BECM repairs yourself.

10. Step-by-step troubleshooting

  1. Confirm the stored DTC and its status in the BECM; TJ 33931 lists U029A00 as intermittent.
  2. Have a service provider check whether the applicable BECM Software Product is installed.
  3. Where applicable, follow the journal direction to update vehicle software according to TJ 31543 before applying the software product.

11. When to contact service

Service is appropriate because the verified Volvo guidance is a BECM software product update. The evidence does not establish urgency or driving/charging status, so a service provider should assess the vehicle’s current warnings, diagnostic results, and software applicability.

12. What the service center may check

  • Read BECM diagnostic trouble codes and confirm U029A00 status.
  • Check the latest online version of Volvo TJ 33931, as the journal instructs users of printed copies to do so.
  • Determine whether the vehicle requires the prerequisite vehicle-software update referenced as TJ 31543.
  • Verify applicability and install the relevant BECM Software Product through authorized service procedures.

13. Possible repair or resolution

  • Update the BECM software using the applicable Volvo Software Product.
  • One TJ 33931 version instructs updating vehicle software per TJ 31543 before the software product is applied.
  • The supplied evidence does not establish that parts replacement is required.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Volvo Technical Journal 33931 / 33931b / 33931c / 33931.4.0, published through NHTSA manufacturer communications. It identifies U029A00 as “Lost Communication with Sensor Module,” lists it as an intermittent BECM DTC, and describes an updated BECM software product.
  • NHTSA communication 10234716, TJ33931c, published September 18, 2018: https://static.nhtsa.gov/odi/tsbs/2018/MC-10234716-9999.pdf
  • NHTSA communication 10234713, TJ33931, published July 19, 2019: https://static.nhtsa.gov/odi/tsbs/2019/MC-10234713-9999.pdf
  • NHTSA communication 10234715, TJ33931b, published February 4, 2019: https://static.nhtsa.gov/odi/tsbs/2019/MC-10234715-9999.pdf
  • NHTSA communication 10155200, TJ33931.4.0, published January 17, 2019: https://static.nhtsa.gov/odi/tsbs/2019/MC-10155200-9999.pdf

16. Recall information

  • No recall information was supplied or established by the verified evidence.

17. Official manufacturer information

Verified official evidence consists of NHTSA-hosted Volvo manufacturer communications for Technical Journal 33931. Applicability in the supplied data is US-market Volvo S90 (2017–2019), XC60 (2017–2019), and XC90 (2016–2019). The data contains overlapping XC90 applicability entries for 2016–2019 and 2017–2019.

19. Frequently asked questions

What does Volvo code U029A00 mean?

Volvo TJ 33931 identifies U029A00 as “Lost Communication with Sensor Module.”

Which module lists U029A00?

TJ 33931 lists U029A00 under the Battery Energy Control Module (BECM) and marks its fault type as intermittent.

What is the documented repair direction?

TJ 33931 states that updated BECM software is available via a Software Product. One supplied version instructs updating vehicle software per TJ 31543 before applying that product.

Is it safe to drive or charge?

Not yet established by verified evidence.

Does this apply to every Volvo?

No. The supplied applicability data identifies certain US-market 2016–2019 XC90 and 2017–2019 S90 and XC60 vehicles. A service provider must confirm applicability for a specific vehicle.

20. Sources & verification

Verified
Volvo U029A00: *Update vehicle software as per TJ 31543, then | EV Diagnostics