P0489 EGR valve: signal or voltage too low ("A")

By: Diagno editorial team · Updated: 2026-10-15

P0489 means: EGR valve: signal or voltage too low ("A"). The EGR valve sends part of the exhaust back into the intake to cut emissions. OK to drive, but have it checked soon. The most common repair costs about €45–90 in Estonia, depending on make and model.

What it means

The EGR valve sends part of the exhaust back into the intake to cut emissions. The computer found too much or too little flow, or a fault in the valve's electrics. The signal voltage is too low. Usually a wire is broken, a connector is loose or a wire is shorted to ground.

What you may notice

• Engine light on
• Less power
• Rough idle
• Black smoke on diesels

What could be wrong

1. 1Connector loose, damp or corroded · Wiring or connector repair €45–90
2. 2Wire broken or shorted to ground · Wiring or connector repair €45–90
3. 3Faulty EGR valve · Valve replacement €90–180
4. 4Engine computer fault (rare) · Control unit check and software €150–300

Repair difficulty: Moderate

What you can check yourself

First look at the connector and wiring: anything loose, melted or green with corrosion? Lots of short trips clog the EGR quickly. Sometimes a longer motorway drive helps. You can check the simple things yourself, but the repair is best done in a workshop.

How we fix it

1. We read the fault data on the diagnostic tool and check whether the fault is constant
2. We measure the circuit's supply, ground and signal
3. We repair the wire or replace the connector
4. If the wiring is fine, we replace the EGR valve

Standard SAE description: Exhaust Gas Recirculation "A" Control Circuit Low