DTC P0491 Ford

Description

Case 1 A failure is detected after 22 loops if 1. The original wheel speed does not reach the extrapolated speed or the reference speed (Vref), 2. The number of interrupts from the wheel speed sensor are continuously gt; = 40 per loop. ※ If the original wheel speed changes erratically. Case 2 A failure is detected after 15 confirmations has been counted. ※ Confirmations starts if the comparison between the number of detected and the number of expected pulses shows at least one missing pulse. A confirmation counter will be incremented if the erroneous speed signal characteristic is detected.