OBD Operation Summary for Fiesta - MotorCraftService.com

Knock SensorTwo basic diagnostic tests are performed on each knock sensor – circuit continuity tests and a knock processing chiptests.Due to the design of the knock sensor input circuitry, after filtering and integration, a short to battery, short toground, or open circuit all result is a low knock signal voltage. This voltage is compared to a noise signalthreshold (function of rpm) to determine knock sensor circuit high and circuit low faults.Another indication of a sensor failure is the standard deviation of the signal noise which decreases when there isa failure. The knock signal standard deviation is compared to a threshold (function of rpm).The knock signal processing chip SPI bus is checked to make sure it is not off. This would indicate there is nocommunication between the main processor and the chip used as the interface the knock sensor.Knock Sensor Check Operation:DTCsMonitor executionMonitor SequenceSensors OKMonitoring DurationP0325 – Knock Sensor 1 CircuitP0326 – Knock Sensor 1 Circuit/Range PerformanceP0330 – Knock Sensor 2 CircuitP0331 – Knock Sensor 2 Circuit/Range PerformanceP06B6 - Internal Control Module Knock Sensor Processor 1 PerformanceContinuous within entry conditionsNoneP0326, P0330,P03312.5 secondsTypical Knock Sensor check entry conditions:Entry Condition Minimum MaximumIgnition “ON”Engine Coolant Temperature 42 °CMass Air FlowEngine speed158 mg/stroke1088 rpmTypical Knock Sensor functional check malfunction thresholds:P0325 & P0330Knock signal too low (function of engine speed): < 0.3516 VP0326 & P0331Knock signal standard deviation too low (function of engine speed): < 0.0195 V to 0.0586VP06B6SPI bus failureCONTINENTAL REVISED: SEPTEMBER 17, 2010 PAGE 97 OF 111