DTC U0109:00, U0109:01, U0109:02 [MZI-3.7]: Notes

WARNING: This page is about a different car, the 2009 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

DETECTION CONDITION & POSSIBLE CAUSE

DTC U0109:00 DTC U0109:01 DTC U0109:02	Lost communication with fuel pump control module
DETECTION CONDITION	The PCM monitors the fuel pump monitor (FPM) circuit for the presence of a duty cycled signal. If the FPM circuit is fixed at a low or high voltage, the PCM begins to increment a counter. The test fails if the PCM is still not detecting a duty cycled signal on the FPM circuit after a calibrated amount of time.
POSSIBLE CAUSE	Open circuit between electronic fuel pump relay terminal D and PCM terminal 1H Short to ground between electronic fuel pump relay terminal D and PCM terminal 1H Short to power supply between electronic fuel pump relay terminal D and PCM terminal 1H Open circuit between electronic fuel pump relay terminal G and fuel pump relay Open circuit between electronic fuel pump relay terminal A and body ground Fuel pump relay malfunction
Courtesy of MAZDA MOTORS CORP.