Stuart Lancaster has pledged to "make it absolutely crystal clear" to Dylan Hartley that any more lapses in discipline could blow England's Six Nations chances.
Hartley was hit with a three-week ban after being sent off for elbowing Leicester centre Matt Smith in Northampton's 23-19 Premiership victory on December 20.
The 28-year-old's latest ban took his career suspension tally to 50 weeks, adding to a rap sheet that includes eye-gouging, biting, punching and swearing.
Lancaster will remind Hartley of his responsibilities to hold his temper, especially when England open their Six Nations campaign in the pressure-cooker Millennium Stadium atmosphere against Wales on Friday, February 6.
"(England forwards coach) Graham (Rowntree) spoke to him and I'm going to speak to him," said Lancaster.
"If you give away dumb penalties clearly it's going to compromise your chances of winning, particularly against Wales, who have Leigh Halfpenny who can kick goals from everywhere.
"I'll be making it absolutely crystal clear to Dylan, one to one, but also the team, that discipline has to be top-notch."
Lancaster had vowed Hartley was in the "last-chance saloon" after his red card for swearing at referee Wayne Barnes during the 2013 Premiership final.
That dismissal led to an 11-week suspension that cost Hartley his place on the Lions tour to Australia.
Lancaster was furious with Hartley for conceding a cheap yellow card in the 31-28 defeat to South Africa in November, and will not accept any repeat.
"I'll speak to Dylan individually about all that," the England supremo reiterated.