VIDEO

Informace

Ford

Ford P0491

See the basic definition of a diagnostic error. This will help you to clarify the main causes of the fault code. You will understand the program of the control unit
Basic DTC analysis according to OBD2 protocol standard.

OBD2 or On-Board Diagnostics displays messages for basic group styles. More comprehensible code composition has been standard since 2000. The DTC code consists of five characters and its composition will be shown in this video

Insight into programming

The basic unit for the operation of any computer is the bit. Logic 0 and 1 are expressed by a single bit. Diagnostics The error code is composed of 16 bits. The first two bits define one of the four basic circuits. The video will show you a comprehensive overview of the composition of the error report

A diagnostically understandable description of the Diagnostic Trouble Code

Ford P0491

Basic error definition

Left Rear Wheel Speed Sensor Signal Range Performance Intermittent

Cause of DTC

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.