What does it mean?
This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996 and newer), although specific repair steps may vary slightly by model.
There are different EGR (Exhaust Gas Recirculation) system designs, but they all function similarly. The EGR valve is a PCM (Powertrain Control Module) controlled valve that allows measured amounts of exhaust gas to return to the cylinders to be burned with the air/fuel mixture. Since exhaust gas is an inert gas that displaces oxygen, reintroducing it into the cylinder can lower combustion temperatures, which helps improve NOx (Nitrogen Oxides) emissions.
The EGR is not needed during cold starts or at idle. The EGR is activated under certain conditions like startup or idle. The EGR is controlled in specific conditions such as partial acceleration or deceleration depending on engine temperature and load, etc. Exhaust gases are supplied to the EGR valve from an exhaust pipe, or the EGR valve may be mounted directly in the exhaust manifold. When needed, the valve is turned “on,” allowing gases to flow into the cylinders. Some systems divert exhaust gases directly into the cylinders, while others simply inject them into the intake manifold where they are then drawn into the cylinders.
Some EGR systems are quite simple, while others are a bit more complex. Electrically controlled EGR valves are directly controlled by the PCM. A wiring harness plugs into the valve itself and is controlled by the PCM as needed. These may have 4 or 5 wires. Usually, 1 or 2 12-volt ignition power grounds, a 5-volt reference circuit, and a feedback circuit. Other systems are vacuum-controlled. These are fairly simple. The PCM controls a vacuum solenoid that, when activated, allows vacuum to move to the EGR valve and open it. There should also be an electrical connector on this type of EGR valve for the feedback circuit. The EGR system feedback circuit allows the PCM to see if the EGR valve pintle is actually moving as it should.
If the EGR “C” feedback circuit detects that the voltage is abnormally low, or its position is lower than commanded, P044C may be set. Refer to a vehicle-specific repair manual for the location of your “C” sensor.
Related EGR “C” Sensor Fault Codes:
- P044A Exhaust Gas Recirculation “C” Sensor Circuit
- P044B Exhaust Gas Recirculation “C” Sensor Circuit Range/Performance
- P044D Exhaust Gas Recirculation “C” Sensor Circuit High
- P044E Exhaust Gas Recirculation “C” Sensor Circuit Intermittent/Erratic
Symptoms
Symptoms of a P044C DTC may include:
- MIL (Malfunction Indicator Lamp) illumination
Causes
Potential causes of a P044C code include:
- Short to ground in the EGR signal or reference circuits
- Short to voltage in the ground or EGR signal circuits
- Faulty EGR valve
- Bad PCM wiring issues due to chafing or loose terminals
Possible Solutions
If you have access to a scan tool, you can command the EGR valve. If it responds and the feedback indicates the valve is moving correctly, the problem may be intermittent. Sometimes in cold weather, moisture can freeze in the valve and cause it to stick. Once the vehicle warms up, the issue may go away. Carbon or other debris can lodge in a valve, which can also cause it to stick.
If the EGR valve does not respond to your commands with the scan tool, unplug the EGR harness connector. Turn the key to the on position, engine off (KOEO). Using a voltmeter, check for 5 volts on the EGR valve reference wire. If there is no 5 volts, is there any voltage at all? If there is 12 volts, repair the short to voltage in the 5-volt reference circuit. If there is no voltage, connect a test light to battery voltage and probe the 5-volt reference wire. If the test light illuminates, the 5-volt reference circuit is shorted to ground. Repair as necessary. If the test light does not illuminate, check for an open in the 5-volt reference circuit. Repair as necessary.
If there is no apparent issue and there is no 5-volt reference, the PCM may be at fault, but other codes will likely be present. If 5 volts are present on the reference circuit, connect the 5 volts to the EGR signal circuit. Now, the EGR position on the scan tool should read 100%. If it does not, connect the test light to battery voltage and probe the EGR signal circuit. If it lights up, the signal circuit is shorted to ground. Repair as necessary. If the light does not illuminate, look for an open in the EGR signal circuit. Repair as necessary.
If, after connecting the 5-volt reference circuit to the EGR signal circuit, the scan tool EGR position reads 100 percent, check the terminal voltage at the EGR valve connector. If the wiring is correct, replace the EGR valve.