Guerra, from Mexico, had been on course for his second consecutive podium finish in his Mitsubishi Lancer only to hit trouble two kilometres into the final 4.36-kilometre Power Stage.
It meant Michal Kosciuszko snatched third place to complete a remarkable recovery after the Pole retired his Mitsubishi Lancer on Friday night heading to parc ferme in Cardiff following an electrical failure on the road section three kilometres from the Welsh capital.
“It’s great for me but it’s really disappointing for Benito because he’s a nice guy,” said Kosciuszko, who also overtook Peruvian champion Nicolas Fuchs on the final run after surviving a small off-road moment of his own on stage 20.
Sweden’s Patrik Flodin secured second in the overall PWRC drivers’ standings with his second victory in as many events at the wheel of his Uspenskiy Rally Tecnica Subaru Impreza, his first start with stand-in co-driver Timo Alanne, from Finland.
“It’s very nice to win the last round and finish the season with some good results,” said Flodin. “I’m very, very happy and must thank Timo who did a very good job. The stages were fantastic today, and it was actually quite an easy day keeping our concentration with such a big lead.”
Czech Martin Semerad took second in his Lancer, almost six minutes adrift of Flodin. Behind Fuchs and fifth-placed Dmitry Tagirov, Abu Dhabi’s Majed Al Shamsi was an impressive sixth after he recovered from an overshoot on Sunday’s first stage.
Ukrainian Aleksey Kikireshko finished seventh with Briton Harry Hunt eighth in his two-wheel-drive Citroen DS3 R3T, his second top 10 finish of the season.
Oleksandr Saliuk endured a tough final morning in his Mentos Ascania Racing Mitsubishi but battled on to finish ninth, one place ahead of team-mate Valeriy Gorban, who crashed out on Saturday’s penultimate stage and restarted under SupeRally regulations today.
“We had a rear right puncture on stage 19, we didn't change it and we lost about two minutes by driving on it,” said Saliuk, who retired on Saturday when his car wouldn’t restart after he overshot a junction.