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Error Code P0487 Exhaust Gas Recirculation Throttle Control Circuit A is open. Meaning, the vehicle’s computer was not able to register the right amount of air pressure in manifold because of a malfunction.
This error code is a generic code that typically applies to diesel engines built since 2004, including but not limited to Dodge, Ford, GM, Mercedes Benz, Mitsubishi, Nissan, Suzuki, and Volkswagen vehicles. Specifications on the definition, troubleshooting and repairs, of course, vary from one make/model to another.
The valve is located between the intake manifold and the air filter, similar to the throttle body. It works by making a small vacuum to draw exhaust gas into the intake manifold. The PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) tells the EGR (Exhaust Gas Recirculation) throttle control valve where it should position itself. Error Code P0487 appears the PCM was not able to register the right amount of air pressure in the manifold when the EGR valve opened.
Depending on the make and model of the vehicle, it may use the EGR position sensor or may measure manifold air pressure and exhaust feedback to ensure there is the right amount of air pressure.
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory. In some cases, the vehicle may exhibit other symptoms, such as:
- Engine running rough
- Hesitation under acceleration
- Increase fuel consumption
This code can be caused by multiple things which are common across virtually all vehicles, such as:
- Defective MAP sensor
- Defective EGR valve
- Defective EGR control solenoid
- Blocked or clogged passage within the EGR valve
- Broken or damaged vacuum line
- Blocked DPFE sensor passages (common among Ford vehicles)
How to Check
As with many error codes, the first step to diagnose this code is to connect the OBD-II scanner to the vehicle’s computer and retrieve the stored codes. Next, mechanics proceed on taking the vehicle for a test drive to see if the code returns.
Next, they conduct a visual inspection of all the vacuum lines in the EGR system. A damaged line is the most common reason for this code. After checking the vacuum lines, all connections and wirings must be checked as well. Any damage must be repaired, if not replaced.
If there is enough vacuum for the system, the EGR valve should be checked next. Some units contain solenoid itself while still separate on other vehicles. The solenoid should be properly diagnosed, followed an inspection to determine whether the EGR valve is blocked or clogged. It’s important to remember that all EGR valve is electronic, not vacuum operated. Thus, mechanics will have to use a scanner to run the EGR for testing as the engine idles.
If the EGR valve is in good working condition, then there’s a good chance the problem lies within the EGR passages in the throttle body.
How to Fix
Common repairs for this code include:
- Repair or replacement of damaged connections and wires in the EGR system
- Replacement of damaged vacuum lines
- Replacement of EGR valve
- Replacement of defective solenoid
- Cleaning and unclogging of the EGR passages
In many cases, the error code P0487 may not directly affect the drivability of the vehicle. It is, however, very possible for the vehicle to exhibit performance problems such as hesitation or lack of power upon acceleration and rough running.
The most common mistake in diagnosing this code is immediately assuming that the problem is caused by a problematic EGR valve. While valve failure is common, there are more usual problems, such as damaged vacuum lines or defective solenoid. Thus, make sure you diagnose thoroughly before making any replacements.