Possible causes – Dirty Fuel Injector 5– Faulty Fuel Injector 5– Plugged Fuel Injector 5– Fuel injector 5 harness is open or shorted– Fuel injector 5 circuit poor electrical connection Tech notes Clogged or partially clogged fuel injector can cause

Possible causes – Dirty Fuel Injector 6– Faulty Fuel Injector 6– Plugged Fuel Injector 6– Fuel injector 6 harness is open or shorted– Fuel injector 6 circuit poor electrical connection Tech notes Clogged or partially clogged fuel injector can cause

Possible causes – Dirty Fuel Injector 6– Faulty Fuel Injector 6– Plugged Fuel Injector 6– Fuel injector 6 harness is open or shorted– Fuel injector 6 circuit poor electrical connection Tech notes Clogged or partially clogged fuel injector can cause

Possible causes – Dirty Oil– Engine mechanical problems– Camshaft timing incorrectly set– Faulty camshaft position sensor– Faulty crankshaft position sensor Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – Dirty Oil– Engine mechanical problems– Camshaft timing incorrectly set– Faulty camshaft position sensor– Faulty crankshaft position sensor Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – Dirty Oil– Low engine oil level– Variable cam timing actuator stuck in retard position– Timing belt jumped Symptoms – Engine Light ON (or Service Engine Soon Warning Light)– Possible Lack/Loss of power– Possible Engine rough idle MAZDA

Possible causes – Dirty throttle body– Electric throttle control actuator misadjusted or damaged– Faulty Electric throttle control actuator– Intake air leak– Poor electrical connection to the Intake Air Control (IAC) valve Tech notes If there are no intake leaks, clean

Possible causes – Dirty throttle body– Electric throttle control actuator misadjusted or damaged– Faulty Electric throttle control actuator– Intake air leak– Poor electrical connection to the Intake Air Control (IAC) valve Tech notes If there are no intake leaks, clean

Possible causes – Dirty transmission fluid– Low transmission fluid level– Faulty line pressure solenoid valve ‘A’– Line pressure solenoid valve ‘A’ harness is open or shorted– Line pressure solenoid valve ‘A’ circuit poor electrical connection When is the code detected?

Possible causes – Drive-by-wire control system malfunction– Throttle actuator malfunction– Throttle valve malfunction– PCM malfunction Tech notes Dirty or clogged throttle body can triggered the P0638 code. Before replacing any parts try cleaning the throttle body and reset the engine

Possible causes – Drive-by-wire control system malfunction– Throttle actuator malfunction– Throttle valve malfunction– PCM malfunction Tech notes Dirty or clogged throttle body can triggered the P0639 code. Before replacing any parts try cleaning the throttle body and reset the engine

Possible causes – ECM Harness power supply circuit is open or shorted– ECM Programing– Faulty ECM Tech notes Check the ECM fuse, if fuse is OK try erasing the code first and if the code comes back you may have

Possible causes – ECM/TCM programming error

Possible causes – ECM/TCM programming error Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – EGR passage clogged– Faulty EGR Vacuum Modulator Valve– Faulty EGR Valve– Faulty EGR solenoid valve– EGR solenoid valve harness is open or shorted– EGR solenoid valve circuit poor electrical connection– Dead (Weak) battery– Faulty EGR temperature sensor

Possible causes – EGR Valve clogged, dirty or leaky– EGR valve damaged/defective– EGR volume control solenoid valve– EGR temperature sensor and circuit– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical

Possible causes – EGR volume control solenoid valve– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical connection– EGR temperature sensor and circuit When is the code detected? An improper voltage

Possible causes – EGR volume control solenoid valve– EGR volume control solenoid valve harness is open or shorted– EGR volume control solenoid valve circuit poor electrical connection– EGR temperature sensor and circuit When is the code detected? An improper voltage

Possible causes – EGR volume control valve stuck open– Faulty EGR volume control valve– EGR solenoid valve harness is open or shorted– EGR solenoid valve circuit poor electrical connection– Faulty EGR temperature sensor and circuit When is the code detected?

Possible causes – Engine Control Module (ECM) Harness power supply circuit is open or shorted– Engine Control Module (ECM) Programming– Faulty Engine Control Module (ECM) Tech notes Check the ECM fuse, if fuse is OK try erasing the code first