BMW reports in federal documents that it will add about another 185,000 vehicles to an existing recall due to increased fire risks thanks to a potential defect within the heater.

The automaker writes in documents filed with the National Highway Traffic Safety Administration that it received “several field incident" reports in 2018 concerning 2006 BMW 3 series models.

Related: BMW issues two recalls covering 1.4M vehicles due to risk of fires under the hood

In all, the German automaker is adding model year 2006 525i, 525xi, 530i, 530xi, 530xi Sports Wagon, 325i, 325xi, 325xi Sports Wagon, 330i, 330xi, Z4 3.0i and Z4 3.0si vehicles to the recall list. The risk in affected models comes thanks to the risk the “heater for the positive crankcase ventilation valve” could short circuit.

In layman’s terms, the plastic coating could overheat and increase the risk of fire within the positive crankcase ventilation valve heater.

“This recall involves the Positive Crankcase Ventilation (PCV) valve heater (blow-by-heater) which may not have been produced to specifications,” BMW reports in federal documents.

“The electrical contacts at the copper tube, and the tube itself, are coated with a plastic material. Irregularities in the manufacturing process at the supplier could lead to cavities in the area of the electrical contacts, and near the PTC element at the copper tube, which could allow moisture to occur and could lead to a short circuit.”

Related: BMW prepared to recall 1.6M globally due to increased fire risk

The Associated Press reports that this expansion to the previous recall brings the number of affected vehicles up to about 925,000.

Previously recalled models include the 2007-2011 328i, 328xi, 328i xDrive, 525i, 525xi, 528i, 528xi, 530i, 530xi, X3 3.0si, X3 xDrive30i, X5 xDrive30i, and Z4.

Affected owners will start being notified of the recall starting May 28 via the mail. Once this happens, dealers will replace the valve heater free of charge.

The automaker can be contacted at 800-525-7417, and the NHTSA at 888-327-4236 concerning the recall (an expansion of recall 17V-683).

To search active recalls, use the NHTSA’s website to search your 17-character VIN at this link. VIN numbers are typically located under the driver’s side windshield, or along the inside of the doors behind the seat or under the steering wheel. To sign up for NHTSA safety alerts for a specific vehicle, sign up at this link.