Service bulletin 21901

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

NHTSA's summary

The Environmental Protection Agency (EPA) and California Air Resources Board (CARB) have approved an emergency calibration to provide temporary relief from the global supply shortage of electrical components. When there is a communication fault in the DEF head unit / Quality Level Sensor (QLS) this temporary calibration will allow the vehicle to operate. The procedure in this document will include diagnosing the DEF head unit / QLS and if found to be defective will advise to install the temporary engine calibration if replacement parts are not available. Any vehicle that receives this calibration will be required to have it removed and a new QLS installed once parts become available, this will be managed through future communication.

The document

• NHTSA's copy of the document (PDF)
• If that address does not open, try this one

The document is the manufacturer's. This site does not hold it. NHTSA files a document at one of these two addresses; we have not asked NHTSA which.

Components

Engine

Listing a model year does not mean every vehicle of it is concerned: the document says which.

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