A Ram stores B0090-49 when the left frontal acceleration sensor reports that its own electronics have failed. The sensor is still connected and still answering, and what it is saying is that the module should stop trusting its readings.
Frontal acceleration sensors sit at the front of the truck and tell the Occupant Restraint Controller how hard it is decelerating. Each sensor runs an internal self test on every key cycle. When the left sensor fails that test, it flags the result, and the ORC logs B0090-49 against that position and disables deployment.
The -49 failure type means internal electronic failure, which is the sensor's own diagnosis rather than a wiring complaint. That narrows the search a great deal. Wiring problems on the same sensor carry different suffixes, so a -49 usually ends with the part being replaced once you have confirmed the supply voltage and ground reaching it are clean and steady.
This is a hardware fault a component is reporting about itself, not a crash record. The sensor repeats the same message on every key cycle until the part is replaced. Crash data is a different animal. It gets written once after airbags fire, stays latched in the ORC, and is the part a mail-in reset erases.
A module reset does not repair a sensor. If the ORC is also holding deployment data from a front impact, mailing us the module clears that crash record, and the failed sensor still has to come off the truck before the lamp goes out. Order of work matters here: replace the sensor, repair whatever the impact damaged, then send the module in.
Ram carries B0090-49 in our lookup. Chrysler built restraint systems assign a base B code to the part and a suffix to the failure type, so you will see B0090 with other suffixes when the complaint is the harness rather than the sensor's own electronics.
Read the code with the suffix attached, because B0090 with a different failure type sends you to the wiring instead of the part. Next, get eyes on the sensor. Front sensors take the weather, so look at the connector for corrosion and at the bracket for impact damage. A sensor reporting its own internal failure gets replaced with a genuine OEM unit, and we can confirm the right one by VIN at 501-988-0611. Related codes: B007F-11, B0090-87, B1695.
Mail us your original module. We restore it to factory-ready condition for a fraction of dealer cost, the same way we have since 1997.
Genuine OEM, tested, and shipped ground from Jacksonville, Arkansas.
Do not see it listed? Request a part or call 501-988-0611.