What Does This Code Mean?
The generic diagnostic code P0487, related to the powertrain/engine, primarily concerns diesel engines manufactured after 2004. It can affect various vehicle models, including those from Ford, Dodge, GM, Mercedes, Mitsubishi, Nissan, Suzuki, and Volkswagen.
The valve in question is located between the intake manifold and the air filter and operates similarly to a throttle body. Its role is to create a slight vacuum to draw exhaust gases into the intake manifold.
The Powertrain Control Module (PCM) controls the position of this Exhaust Gas Recirculation (EGR) control valve. Code P0487 is generated when the PCM detects an inconsistency in the voltage signals sent by the valve, indicating an electrical fault in the circuit.
Diagnostic procedures may vary depending on the manufacturer, the type of EGR valve used, and the wiring configuration.
Symptoms
Symptoms associated with engine code P0487 may include:
- Illumination of the Malfunction Indicator Lamp (MIL) on the dashboard
- Longer than normal post-treatment regeneration time (the exhaust system will take longer to reach the necessary temperature to burn soot deposits in the diesel particulate filter or catalyst)
Possible Causes
Among the most common causes for this code are:
- Break in the signal circuit between the EGR control valve and the PCM
- Short to voltage in the EGR valve signal circuit
- Short to ground in the same circuit
- Internal failure of the EGR control valve
- PCM failure (although this is rare)
Diagnosis and Repairs
To begin, it is recommended to consult the technical service bulletins (TSBs) specific to your vehicle. Some known issues may already have manufacturer-proposed solutions, saving you time and money.
Here are the steps to follow:
- Locate the EGR Control Valve: It is usually located between the intake manifold and the air filter, similar to a throttle body.
- Visual Inspection: Carefully examine the connectors and wiring. Look for damaged, burned, melted, or corroded wires. Disconnect the connectors and check the condition of the metal terminals. Clean them if necessary with a specific electrical contact cleaner, then apply dielectric grease to prevent oxidation.
- Clear the Codes: If you have a diagnostic tool, clear the code and check if it reappears. If it does not return, a connection issue was likely the cause of the error.
- Electrical Tests:
- Disconnect the EGR control valve harness.
- With a digital multimeter (DVOM), measure the voltage on the signal circuit (red lead on the signal, black lead on a good ground).
- If no voltage (normally 5V) is present or if an abnormal voltage (e.g., 12V) is detected, the problem likely lies with the wiring or the PCM.
- Ground Check:
- Use a test light connected to the positive terminal of the battery.
- Test the valve’s ground circuit.
- If the test light does not illuminate, the problem is related to the ground.
- If it lights up but flickers when you move the harness, this indicates a poor connection.
- Valve Replacement:
If all tests are satisfactory and the P0487 code persists, the EGR control valve is likely defective. However, it is important not to completely rule out a PCM failure before replacing the valve.