Labor backbencher Bec Cody has reported herself to the police after she rode her motorcycle home without an L-plate on Tuesday.

Ms Cody, who got her learner motorcycle licence in February this year, was seen by the Canberra Liberals riding her Harley Davidson custom 1200 Speedster out of the ACT Legislative Assembly car park without her plates.

The Liberals alerted the Canberra Times, which asked Ms Cody about the alleged infraction.

Ms Cody said she forgot to put the plate on, and it was the first time she had ridden without one.

"I'm sure everyone's human and they forget to do things occasionally, so that's my only offence," Ms Cody said.

Asked what action she intended to take, such as reporting to police, Ms Cody initially said she was not sure what she would do, and later said she had decided to self-report. 

"It was an icy morning yesterday so I came in to work by car instead of by bike. Later in the day my husband brought the motorbike in for me to ride home and I am embarrassed to say I forgot to put my L plates back on," Ms Cody said in a statement.

"When I got home and realised my mistake I was mortified. I take my responsibilities very seriously and, in fact, as a learner I find drivers are more considerate when they see the L plates.

"This morning I reported myself to the police. In the event they are unable to issue a fine, I will make a donation of the same amount to a road safety charity.

"To help process my report, I hope anyone who has evidence of my mistake will do the right thing and provide it to police or to me."

Ms Cody said she had also gone to ethics and integrity adviser Stephen Skehill to ask his advice on what, if any, further action she should take.

Under the ACT parliament's code of conduct, all MLAs must avoid any decision or action which may "depreciate" the reputation of the Assembly.

Ms Cody is not the only ACT parliamentarian to have taken to motorbiking, with former Liberal Leader Jeremy Hanson buying a 900cc Triumph Bonneville Street Twin early this year.

Mr Hanson, who has been on his P plates since March, said he had a motorbike licence while on exchange with the British Army in Germany, but had never yet held a full licence in Australia. 

When former Labor deputy Simon Corbell lost preselection in 2015, he, too, took to motorbiking, making his way to and from the parliament in leathers and on his Yamaha for his months in politics.

Mr Corbell resigned in anger after he lost the support of the left faction, with Ms Cody given top spot on the left ticket with the backing of the left unions, and Mr Corbell relegated to third.