Error Code P0489 is defined as Exhaust Gas Recirculation “A” Control Circuit Low. Meaning, the EGR “A” control circuit is sending is reporting a low voltage flow caused by defective wiring or clogged EGR passages.

Definition

This code is a generic trouble code, meaning it applies to all vehicle makes/models equipped with OBD-II system, especially those made since 1996 up to present. Specifications for the troubleshooting and repairs differ from one make and model to another.

This code also specifically refers to a fault in the EGR (Exhaust Gas Recirculation) system’s electrical aspect. When it’s stored, it means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has detected a problem in the EGR system’s electrical component. The EGR works by preventing harmful emissions from escaping into the environment. To keep a cylinder head pressure, the PCM operates the EGR system by opening or closing the EGR valve, depending on the vehicle’s temperature, load, and speed.

The PCM has a specified preset degree which allows chance in the exhaust manifold. If it stops detecting the proper exhaust flow when the EGR is activated, then the Error Code _0489 will be set.

Depending on the make and model of the vehicle, the position of the EGR sensor may be used to monitor the EGR valve, while the PCM determines the desired EGR flow based on how far open the valve is at the time. Some cars measure manifold air pressure and exhaust feedback with a DPFE (Delta Pressure Feedback EGR) sensor.

Other related Error Codes include:

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. And in some cases, the vehicle may not show any symptoms. For cases with symptoms, the common symptoms include:

  • Rough running
  • Choppy idle
  • Increase in fuel consumption
  • Engine hesitates to start or may not start at all
  • Drop in engine power
  • Darker smoke emission in the exhaust

Possible Causes

  • Defective or corroded connectors or wirings
  • Clogged DPFE sensor passages
  • Clogged EGR passages
  • Short to ground
  • Short to battery voltage
  • Damaged or defective EGR system
  • Damaged or defective EGR valve or valve gasket
  • Damaged or defective EGR control solenoid
  • Damaged or defective EGR line
  • Clogged MAP/MAF sensor
  • Broken or damaged vacuum line or hose

How to Check

A common start for diagnosing this code is by the use of an OBD-II scanner to check for the stored code.

Next, technicians proceed on checking all the wiring, electrical connectors, and harnesses for damaged or defects.

Then they inspect the connectors, vacuum hoses, and lines for leaks or any signs of damage.

Next, they determine how the EGR valve is controlled by the PCM or vacuum.

They also monitor the EGR function and compare it with the recommendations set by the manufacturer.

Next, they determine whether the EGR valve is sticking or not. They will have to use a handheld vacuum pump to observe the EGR operation to determine if the valve opens.

If the vehicle doesn’t stall when the valve opens, they will have to check for clogged EGR passages.

If the engine stalls, then they will have to check the EGR control solenoid if it’s working.

Next, they will test the EGR control solenoid connector for a voltage and the ground signal.

Next, they will test the voltage signal between the PCM and the EGR electrical connector.

Lastly, technicians will check for signs of damage, burnt, or loose wiring at the EGR valve and control solenoid, or the EGR and the DPFE sensor.

How to Fix

Depending on the diagnosis, the common repairs for this code include:

  • Repair or replacement of damage or loose connectors, harnesses, and wirings
  • Repair or replacement of broken and leaking vacuum hoses and lines
  • Repair or replacement of damaged or faulty EGR control solenoid
  • Cleaning the EGR passages off of carbon
  • Clearing the codes, test drive the vehicle and rescan to see if the codes reappear
  • Replacement of damaged or defective EGR valve

 

EGR valve replacement is expensive, and in many cases, the problem is simply caused by a blown gasket or damaged wiring, which is why it’s important to conduct a thorough diagnosis.