The US National Highway Traffic Safety Administration (NHTSA) is discussing with Tesla its decision to replace cameras in some vehicles.
CNBC reported last week Tesla was replacing front fender cameras in several hundred Model S, X and 3 vehicles due to faulty circuit boards inside, but had not issued a recall.
NHTSA said it is "monitoring all data sources" including consumer complaints, and also urged "the public to let NHTSA know if they think their vehicle may have a safety defect that isn’t part of a current recall".
US law "prohibits manufacturers from selling vehicles with design defects posing unreasonable risks to safety", the agency said, adding it has "robust enforcement tools to protect the public, to investigate potential safety issues, and act when we find evidence of noncompliance or an unreasonable risk to safety".
Consumer groups said the regulator needs to look into whether Tesla should have recalled the defective parts.
"Reports of a service campaign repair to malfunctioning front-end cameras that are critical to Tesla's driver assistance suite is important enough to the safety of the vehicle to merit exploration by NHTSA," said Jason K Levine, executive director at Center for Auto Safety.
"The reality is that the auto industry has a long history of choosing to conduct service campaigns instead of recalls, but it is too early to say whether that’s the case here.”
A malfunction of front fender cameras, safety systems used for blind spot monitoring, would likely create a safety risk, said David Friedman, a former acting administration at NHTSA and now vice president at Consumer Reports.
"If people are losing reliable access to blind spot images, or the effectiveness of autopilot or automatic emergency braking is being hampered, the malfunction would seem to pose an unreasonable risk," he said.
Tesla was not immediately available for comment.
The NHTSA is already investigating the company over multiple crashes involving its AutoPilot driver aid system which, despite the name, doesn't offer autonomous driving.
The agency has also written to Tesla asking why a required previous software update didn't end up with a recall of its cars, saying it wanted to know the "technical and/or legal basis for declining".
And just last week it said it was in discussions with the company after a software update allowed drivers to play video games while the car is being driven.
Mercedes-Benz has just issued a recall for a similar issue, drawing concerns that different car manufacturers are treated differently.
The German company issued a US recall for 277 vehicles that allowed drivers to access videos and the internet while the car was in motion.
Philip Koopman, a professor of electrical and computer engineering at Carnegie Mellon University said Mercedes-Benz was following the regulatory rules, in contrast to what Tesla were doing.
If the NHTSA failed to take action against Tesla, the agency would have one standard for the Elon Musk-run company and another for other car makers, he said.
Reuters / Newshub