You can sue the smog tech's repair shop for negligence.  Negligence is the failure to exercise due care (that degree of care that a reasonable smog tech would have exercised under the same or similar circumstances to prevent foreseeable harm).Prior to filing a lawsuit, it may be possible to settle thc case with the smog tech's insurance carrier.  It would also be advisable to ask the smog tech's insurance carrier in writing if it requires you to have the repairs done at a shop authorized by them.If the case is settled with the smog tech's insurance carrier, NO lawsuit is filed.If the case is NOT settled with the smog tech's insurance carrier, file your lawsuit for negligence against the smog tech's shop.As for evidence that the smog tech damaged your car, the repair work done by a mechanic with a declaration (statement in writing signed under penalty of perjury) by the mechanic who repairs your car will be the evidence.