Is P0490 the same as P0405?

No. P0405 is the EGR position sensor reading too low, while P0490 is about the circuit that drives the valve reading too high. Both are electrical, so both start with the connector and wiring, but they point to different circuits.

Can I drive with P0490?

For a short time, yes. The engine runs without working EGR, which can cause rough running, smoke or reduced power, and the emissions system is not working as designed. Have it checked within days, and sooner if power drops.

Is P0490 the wiring or the valve?

It can be either. The harness runs close to hot exhaust parts, so chafed or heat-damaged wiring is a real possibility, but a valve that has shorted inside sets the same code. Measuring the control wire with the valve unplugged tells the two apart before any parts are bought.

Why does P0490 come back after cleaning the EGR valve?

Cleaning removes soot but does not repair an electrical fault. If the code returns within a few kilometres, the problem is more likely the wiring, the connector or the valve's motor than deposits. The circuit needs to be tested.

How much does it cost to fix P0490?

Cleaning and repairing the connector costs roughly 70 to 240 euros fitted. A new EGR valve costs 160 to 600 euros fitted, a wiring repair 120 to 420 euros, and a workshop diagnosis 30 to 80 euros.

P0490: Exhaust Gas Recirculation "A" Control Circuit High

Quick Answer

Safe to drive (short-term)

P0490 means the engine computer sees too high a voltage on the control circuit of the EGR valve, the valve that feeds some exhaust gas back into the intake. On many cars the computer switches the valve by connecting its control wire to ground, so voltage on that wire when it should be grounded points to a short to a power feed or a valve that has shorted inside. It is an electrical code about the valve's drive circuit, unlike P0405 (the position sensor) or P0401 and P0402 (the gas flow).

Severity: Moderate · Emissions
Estimated repair cost: From €30 to €600+, varies by vehicle

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What does P0490 mean?

P0490 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0490 and illuminates the check engine light.

What are the symptoms of P0490?

If your vehicle has triggered P0490, you may notice one or more of these symptoms:

Check engine light on
Rough or hunting idle
Reduced power or limp mode on some diesels
Black or grey smoke on acceleration
Hesitation when pulling away
Fault that returns within a few kilometres after clearing the code
Failing the emissions part of a periodic inspection

What causes P0490?

Here are the most common causes of P0490:

Control wire shorted to a power feed, often where the harness is chafed or heat-damaged near the exhaust
: high
EGR valve motor or solenoid shorted internally
: high
Water or corrosion in the EGR valve connector bridging the pins
: medium
High resistance in the valve's supply or ground wire, or a loose terminal
: low
Engine computer output stage faulty (rare, test the wiring and valve first)
: low

Is it safe to drive with P0490?

Generally yes, for short-term driving. Driveable for a short time. P0490 means the engine computer sees too high a voltage on the circuit it uses to drive the EGR valve, usually because the control wire is shorted to a power feed. The computer then cannot control the valve, so the engine runs without working EGR. Expect a rough idle or smoke, and on some diesels reduced power. Have it checked within days, and stop driving if the car loses power or runs very badly.

How do you diagnose P0490?

Follow these steps to pinpoint the root cause of P0490:

Read all stored codes and the freeze frame. Fix any shared supply or ground codes first. A generic OBD2 reader shows the codes, the freeze frame and, where the car reports it, the standard commanded EGR reading. It cannot switch the valve on and off for a test; that needs manufacturer-level software.
Inspect the EGR valve connector and harness for corrosion, melted insulation and chafing, especially where the harness runs near hot pipework.
Unplug both the EGR valve and the engine computer connector, switch the ignition on and measure the control wire against ground. Any voltage on it then means the wire is shorted to a power feed somewhere in the harness. Do not test with the computer still connected: on some cars the computer itself holds the control wire near battery voltage while the valve is off.
With the ignition off, measure the valve's winding resistance against the workshop figure. A reading close to zero points to an internal short, an open reading to a broken winding.
Check the valve's supply and ground wires for high resistance, and the connector terminals for a loose fit.
If the wiring tests normal and the valve measures correctly, only then suspect the engine computer. That is rare.
After the repair, clear the codes and road-test. Some makes need the new valve learned with manufacturer-level software, which a generic OBD2 reader cannot do.

How much does P0490 cost to fix?

Repair costs for P0490 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Clean and repair EGR valve connector	€10–€60	€60–€180	€70–€240	Moderate
Replace EGR valve (electronic, petrol or diesel)	€100–€400	€60–€200	€160–€600	Moderate
Repair EGR wiring harness section	€20–€120	€100–€300	€120–€420	Professional
Workshop diagnosis (live data and circuit tests)	€0–€0	€30–€80	€30–€80	Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

P0490 on specific vehicles

P0490 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0490 on Opel

Opel Insignia A 2.0 CDTI 160 (A20DTH, also in the Saab 9-5 2.0 TiD)

See Opel-specific causes & cost

These codes are often seen alongside P0490 or indicate related issues:

Common questions about P0490

What does P0490 mean?: P0490 means the engine computer measures too high a voltage on the control circuit that drives the EGR valve. The usual causes are a wire shorted to a power feed or a valve that has shorted inside. The computer then cannot control the valve and may switch EGR off.
Is P0490 the same as P0405?: No. P0405 is the EGR position sensor reading too low, while P0490 is about the circuit that drives the valve reading too high. Both are electrical, so both start with the connector and wiring, but they point to different circuits.
Can I drive with P0490?: For a short time, yes. The engine runs without working EGR, which can cause rough running, smoke or reduced power, and the emissions system is not working as designed. Have it checked within days, and sooner if power drops.
Is P0490 the wiring or the valve?: It can be either. The harness runs close to hot exhaust parts, so chafed or heat-damaged wiring is a real possibility, but a valve that has shorted inside sets the same code. Measuring the control wire with the valve unplugged tells the two apart before any parts are bought.
Why does P0490 come back after cleaning the EGR valve?: Cleaning removes soot but does not repair an electrical fault. If the code returns within a few kilometres, the problem is more likely the wiring, the connector or the valve's motor than deposits. The circuit needs to be tested.
How much does it cost to fix P0490?: Cleaning and repairing the connector costs roughly 70 to 240 euros fitted. A new EGR valve costs 160 to 600 euros fitted, a wiring repair 120 to 420 euros, and a workshop diagnosis 30 to 80 euros.

Read our detailed guides

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