CarFix Answers

2019–2021 Toyota RAV4: 12-volt battery keeps dying overnight

Likely causes, ranked

  1. Data Communication Module staying awake after shutdown (firmware update T-SB-0095-20)$0–$0Shop
  2. Battery damaged by repeated deep discharges (replacement)DIY
  3. Other parasitic draw (relay, aftermarket devices)Shop

Real-owner fix counts will appear here as reports come in.

DIY or shop: See DIY or shop section

Parts to check

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Symptom: The car is completely dead after sitting overnight or for a few days. Nothing electrical works until it's jump-started.

Likely causes

  1. Data Communication Module (DCM). RAV4World owners trace this to the connected-services module staying active after shutdown on 2020–2021 models (and some late 2019s). Toyota's bulletin T-SB-0095-20 resets it and updates its firmware.
  2. A damaged battery. Repeated full drains hurt the 12V battery, so owners recommend asking for a new one too.
  3. Other draws. Some cars still drained after the update, so a measured parasitic-draw test matters.

Cost

The bulletin work is usually covered under warranty. An AGM replacement battery costs extra if it's out of warranty.

DIY or shop?

  • DIY: carry a jump pack, and check resting voltage with a multimeter.
  • Dealer: the firmware update and a draw test.

Useful steps

  1. Ask the dealer for T-SB-0095-20 and whether your VIN qualifies.
  2. After the update, let the car sit 3–4 days to confirm the fix.
  3. Replace the battery with the correct AGM/EFB type.

Vehicle focus: 2019–2021 Toyota RAV4.

Safety / mechanic note

Getting stranded is the main risk. Keep a jump pack in the car until it's fixed.

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Recalls & service bulletins

Technical service bulletins

  • T-SB-0095-20 Toyota DCM reset and firmware update for a depleted 12V battery with the ignition off (2020–2021 RAV4 with the LG DCM). Details

NHTSA complaints: 139 keyword-matched complaints for Toyota RAV4 2019–2021 (of 1,885 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-15).

Always check your VIN for open recalls at nhtsa.gov/recalls.

Sources

What actually fixed it?

Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.

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