P0490

Symptoms

• Check Engine Light Is On
• The EGR valve can be constantly open (gas supply without command)
• Unstable engine operation at idle
• Rough operation or failures during overclocking
• Increased fuel consumption
• Detonation under load
• Black or blue smoke from the exhaust pipe

Causes

• Short circuit of the EGR valve control wire to the +12V circuit
• Turn-to-turn short circuit in the EGR valve solenoid winding
• Faulty control module or relay in the EGR circuit
• Damage to wire insulation due to overheating near the exhaust manifold
• Faulty ECU (EGR control output stage)
• Moisture entering the valve connector

How to Fix

1. Measure EGR valve solenoid resistance - too low indicates a short.
2. Check the voltage on the control wire with the ignition off - it should not be +12V
3. Inspect the wiring harness along the exhaust tract for melting and damage to the insulation.
4. Disconnect the EGR valve connector and check for high voltage on the control wire.
5. Check for other EGR codes for a complete picture of the problem
6. Replace the EGR valve if the solenoid is internally shorted
7. Restore wiring if there is a short circuit in the harness
8. Reset codes and perform adaptation after repair

Related codes

Error P0490 by Vehicle Brand