Possible causes – Dirty Fuel Injector 9– Faulty Fuel Injector 9– Plugged Fuel Injector 9– Fuel injector 9 harness is open or shorted– Fuel injector 9 circuit poor electrical connection Tech notes Clogged or partially clogged fuel injector can cause

Possible causes – Dirty Oil– Engine mechanical problems– Faulty camshaft position sensor– Faulty crankshaft position sensor– Timing belt jumped Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – Dirty Oil– Engine mechanical problems– Faulty camshaft position sensor– Faulty crankshaft position sensor– Timing belt jumped Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – Dirty Oil– Engine mechanical problems– Faulty camshaft position sensor– Faulty crankshaft position sensor– Timing belt jumped Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

Possible causes – Dirty Oil– Engine mechanical problems– Faulty camshaft position sensor– Faulty crankshaft position sensor– Timing belt jumped Symptoms – Engine Light ON (or Service Engine Soon Warning Light)

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 – 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 – EGR solenoid valve harness is open or shorted– EGR solenoid valve circuit poor electrical connection– EGR volume control valve stuck closed– Dead (Weak) battery– Faulty EGR temperature sensor and circuit– Faulty EGR Valve– EGR passage clogged– Exhaust

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

Possible causes – Engine Control Module (ECM) may be faulty– ECM harness power supply circuit is open or shorted– ECM harness ground circuit is open or shorted Tech notes Check the ECM fuse, if fuse is OK try erasing the

Possible causes – Excessive resistance in the circuit– Low or no fuel– Wiring harness connector of the fuel pressure sensor– Fuel Rail Pressure Sensor– Fuel Pump Symptoms – Engine Light ON (or Service Engine Soon Warning Light)– Engine will not

Possible causes – Exhaust Gas Recirculation (EGR) volume control valve stuck closed– Faulty Exhaust Gas Recirculation (EGR) volume control solenoid valve– Faulty EGR Valve– Faulty EGR temperature sensor and circuit– Exhaust Gas Recirculation (EGR) solenoid valve harness is open or

Possible causes – Failed Engine Cooling Thermostat– Engine Cooling Thermostat harness is open or shorted– Engine Cooling Thermostat circuit poor electrical connection Tech notes If there are not coolant system leaks, replaced the thermostat to fix the problem. When is

Possible causes – Failed Engine Cooling Thermostat– Engine Cooling Thermostat harness is open or shorted– Engine Cooling Thermostat circuit poor electrical connection Tech notes If there are not coolant system leaks, replaced the thermostat to fix the problem. When is

Possible causes – Failed Engine Cooling Thermostat– Engine Cooling Thermostat harness is open or shorted– Engine Cooling Thermostat circuit poor electrical connection Tech notes If there are not coolant system leaks, replaced the thermostat to fix the problem. When is

Possible causes – Faulty Air Conditioning Clutch Relay– Air Conditioning Clutch Relay harness is open or shorted– Air Conditioning Clutch Relay circuit poor electrical connection When is the code detected? The P0645 code is stored if an open or short

Possible causes – Faulty Air Pump inoperative– Air bypass solenoid harness is open or shorted– Air bypass solenoid circuit poor electrical connection When is the code detected? The DTC P0412 is detected the the AIR vacuum control solenoid circuit not