Plugged Mazda FTP breather
Some 2011 Mazda2 vehicles may experience MIL illumination with DTC P0451:00 (fuel tank pressure sensor range/performance problem) stored in PCM memory. This may be caused by water or snow entering and freezing in the atmosphere breather hose in the FTP (fuel tank pressure sensor).
Remove the L-shaped atmosphere breather hose (A) from the FTP sensor (B) and inspect for water and/or ice. If water is found, drain the water from the FTP sensor by shaking it. If ice is found, warm up the sensor and drain. Do not use pressurized air to drain water from the FTP sensor to avoid damaging the sensor.
Cut a new hose to 160mm (original length is approximately 999mm).
Peel off and discard the tape (C) on No. 4 cross member. Apply rust preventive paint where the tape was removed and install the new clip.
Remove and discard the original L-shaped breather hose (A) from the FTP sensor (B).
Attach the new hose (160mm in length) to the FTP sensor, then attach the other end of the hose to the new clip (D). Using M-MDS, confirm that FTP sensor PID voltage reading is within 2.5V – 3.6V, then perform EVAP self-test.
If FTP sensor voltage reading is within range and the self-test passes, proceed to the next step. If FTP sensor voltage reading is out of range and the self-test fails, replace the FTP sensor.
Clear the stored DTC in the PCM.