P0490

EGR A Control Circuit High

Auxiliary emissions control Generic OBD-II Medium

What it means

P0490 means the ECM sees an abnormally high voltage on the "A" exhaust gas recirculation (EGR) control circuit — the circuit that drives the EGR valve. EGR routes a little exhaust back into the intake to lower combustion temperatures and emissions. This is typically a wiring, connector, or EGR-valve fault; the car usually still drives, but you may notice rough running and higher emissions until it's fixed.

Medium

Can I keep driving? Yes, but watch it — the car usually drives, though a stuck or mis-controlled EGR valve can cause rough idle, hesitation, and higher emissions; fix it before it worsens.

Real-world scan data

Seen in

356

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0490 scans

P0401in 35.7% of scans

P0409in 25.3% of scans

P1459in 20.5% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on
Rough idle or hesitation
Reduced performance
Increased fuel consumption
May fail an emissions test

Common causes

Most likely first

Open or short-to-voltage in the EGR control circuit wiring (high signal)Likely
Faulty EGR valve / actuatorCommon
Corroded or loose connector at the EGR valve or ECMCommon
Carbon buildup binding the EGR valveLess often
Faulty ECM/PCM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the fault is a high-voltage condition on the EGR A control circuit.
Inspect the EGR valve connector and control wiring for shorts to power, opens, and corrosion.
Command the EGR valve with a scan tool (if supported) and watch it respond.
Inspect the EGR valve for carbon buildup; clean or replace if it's binding.
Repair wiring faults; if the circuit and valve are good, suspect the ECM driver. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0490?+

Usually yes short-term, but a malfunctioning EGR valve can cause rough running and higher emissions, so have it repaired soon.

Can I just clear P0490?+

You can, but it returns until the wiring or EGR valve fault is repaired.

Read & clear P0490 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX