The latest glitch to hit the Edinburgh bank, part-owned by the taxpayer, comes less than a month after hundreds of thousands of RBS, NatWest and Ulster Bank customers had their cards declined due to a problem.
This time, however, the issue was caused by the supermarket.
The error occurred when customers attempted to pay at the pump. After correctly inputting their pin three times, payment was denied and their cards locked.
Stuart Lomas, of Manchester, tweeted: "If you're trying to use RBS cards at Tesco pay at pump petrol stations, it will not work and blames your pin. It is a fault with Tesco systems."
Tesco has apologised and said it was investigating the reports. RBS said there were no problems with its own systems.
On December 10, some 750,000 customers were unable to withdraw cash or pay for purchases for about three hours.