Photo: Toyota / edited
Joined at the hip to the RAV4 Prime, the Lexus NX 450h+ compact luxury crossover and its Toyota-branded sibling have been recalled to the tune of 43,442 units in the United States of America. Said plug-in hybrid sport utility vehicles are equipped with a DC-DC converter with a potentially damaged module that may short circuit, therefore increasing the risk of a fire.
The Japanese automaker became aware of this problem two years ago, back in June 2021, after a field report alleging a flurry of warning messages followed by smoke coming out from the rear seat of a RAV4 Prime. As it happens, the dealer found a damaged plastic cooling duct on the DC-DC converter, which is located under the rear seat of the plug-in hybrid crossover.
Toyota immediately contacted the supplier of the DC-DC converter, namely the Denso Corporation of Japan. The supplier also discovered a damaged electric current rectifying module inside the DC-DC converter, but couldn't determine the root cause behind this issue.
Denso eventually pinned a chip failure caused by damage sustained during manufacturing. The static electrical charge in the manufacturing process of the DC-DC converter might have damaged the electric current rectifying module. Denso replicated this condition in the lab, observing a short circuit in the event of a failed chip. Current from the 12-volt battery continues to flow into the module, generating excessive heat. Said heat melts the cooling duct. In the worst-case scenario, a full-blown vehicle fire can't be ruled out.
For some reason or another, the safety boffins at Toyota claimed that the temperature around the cooling wouldn't reach the ignition point of the cooling duct's material. This rather poor assumption came back to bite Toyota in February 2022, following a report from Canada indicating smoke and burned plastic smells.
Toyota ordered Denso to redesign the rectifier module to eliminate any potential of a short circuit. More specifically, the redesigned module would fail to an open circuit, which doesn't allow the 12-volt battery's current to flow through the module in case of a failure.
Come January 2023, the Japanese automaker identified a clogged breather plug. Toyota ordered yet another series of tests, which confirmed that the current from a sub DC-DC converter within the charger also flows into the module when the vehicle is charging and the high-voltage battery's temperature is low enough to require the heater to be activated. With the breather plug clogged, the temperature in the DC-DC converter became high enough to melt the aluminum housing, therefore allowing the cooling duct to catch fire.
As mentioned, a grand total of 43,442 vehicles are recalled over this fiery concern. Affected RAV4 Prime vehicles were produced for the 2021 and 2022 model years in the period between November 25, 2019 and May 27, 2022. As for the NX 450h+, make that 2022 models from April 07, 2021 through May 27, 2022.
Dealers have been instructed to replace the DC-DC converter at no cost to the owners, with said owners to be informed of the recall by first-class mail between August 7 and September 10. The replacement part features an improved design, according to Toyota.
Toyota immediately contacted the supplier of the DC-DC converter, namely the Denso Corporation of Japan. The supplier also discovered a damaged electric current rectifying module inside the DC-DC converter, but couldn't determine the root cause behind this issue.
Denso eventually pinned a chip failure caused by damage sustained during manufacturing. The static electrical charge in the manufacturing process of the DC-DC converter might have damaged the electric current rectifying module. Denso replicated this condition in the lab, observing a short circuit in the event of a failed chip. Current from the 12-volt battery continues to flow into the module, generating excessive heat. Said heat melts the cooling duct. In the worst-case scenario, a full-blown vehicle fire can't be ruled out.
For some reason or another, the safety boffins at Toyota claimed that the temperature around the cooling wouldn't reach the ignition point of the cooling duct's material. This rather poor assumption came back to bite Toyota in February 2022, following a report from Canada indicating smoke and burned plastic smells.
Toyota ordered Denso to redesign the rectifier module to eliminate any potential of a short circuit. More specifically, the redesigned module would fail to an open circuit, which doesn't allow the 12-volt battery's current to flow through the module in case of a failure.
Come January 2023, the Japanese automaker identified a clogged breather plug. Toyota ordered yet another series of tests, which confirmed that the current from a sub DC-DC converter within the charger also flows into the module when the vehicle is charging and the high-voltage battery's temperature is low enough to require the heater to be activated. With the breather plug clogged, the temperature in the DC-DC converter became high enough to melt the aluminum housing, therefore allowing the cooling duct to catch fire.
As mentioned, a grand total of 43,442 vehicles are recalled over this fiery concern. Affected RAV4 Prime vehicles were produced for the 2021 and 2022 model years in the period between November 25, 2019 and May 27, 2022. As for the NX 450h+, make that 2022 models from April 07, 2021 through May 27, 2022.
Dealers have been instructed to replace the DC-DC converter at no cost to the owners, with said owners to be informed of the recall by first-class mail between August 7 and September 10. The replacement part features an improved design, according to Toyota.
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