Warming Up Frozen Mazda Vent Hose

When the engine is started for the first time after parking overnight in below-freezing temperatures, the check engine light may be on with DTC P0451:00 (fuel tank pressure sensor...sensor characteristic malfunction) stored in memory. This may be caused by an increase in discharge resistance due to water accumulated and frozen in the canister vent hose.

Check if the canister vent hose is clogged with frozen water. If so, cut the evaporative hose No. 1 diagonally to enlarge the cross section to avoid water from accumulating and freezing. Tie the hose No. 1 and the canister hose with a tie-wrap. Clear the DTC and verify the repair. The canister hose is available as P/N PE01-13-971.