Is ISO 17025 accreditation needed?

You asked

I would like to ask if an OEM company is ISO9001:2015 certified is it mandatory that they will get certification for ISO IEC 17025:2017 accreditation?

The answer is no, IATF does not have a mandatory requirement for ISO 17025 accreditation. To clarify this let us start with mentioning that ISO 17025 is a testing and calibration standard to which laboratories are accredited, where ISO 9001 and IATF 16949 are Quality Management standards, to which organizations are certified. IATF 16949 is implemented in conjunction and as a supplement to ISO 9001 with a number of extra requirements for automotive suppliers on top of the requirements of ISO 9001.

An OEM (original equipment manufacturer) that supplies components is not a laboratory, so ISO 17025 is not directly applicable. IATF 16949 however requires that specific laboratory requirements are met and the process for the management and calibration or verification records and internal calibrations is documented. Because of these requirements and the need for statements of conformity to a specification after calibration/verification, IATF 16949 includes an explanatory note that ISO/IEC 17025 accreditation is useful to demonstrate the organization's in-house laboratory conformance to the IATF 16949 requirements. This means that although not mandatory, testing of components and calibrations will typically be be performed by an accredited ISO 17025 laboratory. This is irrespective of  whether it is an inhouse laboratory (owned by or a department of the OEM) or subcontracted to an external provider.

Note that while accreditation is not mandatory; as a minimum, it is advisable that the laboratory implements ISO 17025 and works in accordance to ISO 17025 to ensure requirements are met.

You also asked 

 if answer is No, does it affects company's accreditation to  IATF 16949?

Please note as said above, a company is certified to IATF 16949, not accredited. As long as the specific laboratory requirements are met, accreditation to ISO 17025 will not affect company's certification to IATF 16949

For more information on IATF 16949, see the IATF 16949 Advisera Academy at https://advisera.com/16949academy/
For more information on ISO 17025 see ISO 17025 – Main guidelines at https://advisera.com/17025academy/what-is-iso-17025/