Is P0638 the throttle body?

Usually. A dirty plate, worn motor gears or a faulty sensor inside the throttle body cause most cases. A loose or wet connector sets the same code and costs far less to fix, so it is checked first.

Can I drive with P0638?

Only slowly, to the nearest safe place or workshop. Power is normally cut, and because the fault can come and go, the car may lose power again at a bad moment.

Can P0638 come and go?

Yes. A worn position sensor or a loose connector can drop out briefly, so the car loses power and then drives normally after a restart. An intermittent P0638 still needs fixing, because the next drop-out can happen while overtaking.

Will cleaning the throttle body fix P0638?

It can, if carbon makes the plate drag. Clean it with the ignition off, then run the throttle learn. Cleaning does not help worn gears or a faulty sensor, so if the code returns within days the throttle body needs replacing.

How much does it cost to fix P0638?

Cleaning the throttle body with a learn costs roughly 30 to 90 euros. A connector or wiring repair runs 70 to 220 euros, and a new electronic throttle body 150 to 600 euros fitted. Where the learn needs diagnostic software, add 30 to 80 euros.

P0638: Throttle Actuator Control Range/Performance (Bank 1)

Quick Answer

Not safe to drive

P0638 means the engine computer drives the electronic throttle motor towards a target angle and the throttle does not get there properly: it lags behind, or the motor needs far more drive than a healthy throttle would. Typical reasons are a throttle plate dragging in carbon, worn motor gears, a position sensor inside the housing that reports the wrong angle, or a poor connection. On an engine with a single throttle body, "bank 1" simply means that throttle.

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

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What does P0638 mean?

P0638 is a electrical-related diagnostic trouble code classified as high severity. When your vehicle's ECU detects this condition, it stores P0638 and illuminates the check engine light.

What are the symptoms of P0638?

If your vehicle has triggered P0638, you may notice one or more of these symptoms:

Check engine light, often with a reduced power or engine fault message
Engine held at low power or near idle until it is restarted
Power cutting out briefly while driving, then coming back
Poor or delayed response to the accelerator
Idle speed rising and falling on its own
Smoke at start-up on some diesels with an electronic intake throttle

What causes P0638?

Here are the most common causes of P0638:

Carbon and oil on the throttle plate and bore, so the motor has to push harder to move it
: high
Worn motor brushes or gears in the throttle body
: high
Faulty position sensor inside the throttle body, so the computer drives the motor against a wrong angle reading
: medium
Loose, corroded or wet connector, or a damaged wire in the throttle motor circuit
: medium
Plate held open by something in the bore, or a return spring that no longer closes it
: low
Engine computer fault (rare, check everything else first)
: low

Is it safe to drive with P0638?

No - address this immediately. Not safe for normal driving. P0638 means the engine computer is struggling to drive the electronic throttle: the motor needs far more effort than normal, or the throttle does not reach the angle asked for. Most cars then cut power or hold the engine near idle, and on some the power drops without warning. Drive slowly to a safe place or a nearby workshop, and do not overtake, join a motorway or tow a trailer.

How do you diagnose P0638?

Follow these steps to pinpoint the root cause of P0638:

Read all codes and the freeze frame. A throttle or pedal sensor code stored alongside, such as P0121, P0122 or P2135, is dealt with first, because the computer cannot steer the throttle with a wrong angle reading.
On a generic OBD2 reader, watch throttle position together with commanded throttle actuator, a standard reading many cars report. If the commanded value rises but the throttle position lags well behind or barely moves, the plate is sticking or the motor is wearing out.
With the ignition off and the intake hose removed, check the plate. It should sit at its resting angle, move smoothly against the spring and return on its own. A plate that binds, does not return, or moves with no spring force needs cleaning or a new throttle body.
Inspect the connector and harness for loose pins, corrosion and water, then check the motor wires for opens, shorts and high resistance with a multimeter and the wiring diagram.
If the plate is clean and free and the wiring is good, the motor, its gears or the position sensor inside the housing have failed. These are usually sold only as a complete throttle body.
After cleaning or fitting a new throttle body, clear the codes and run the throttle learn the make requires. Some makes use a sequence of key and pedal steps, others need manufacturer-level software. Then road-test.

How much does P0638 cost to fix?

Repair costs for P0638 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Clean throttle body and run the throttle learn	€0–€10	€30–€80	€30–€90	Easy
Repair throttle body wiring or connector	€10–€40	€60–€180	€70–€220	Moderate
Replace electronic throttle body	€120–€450	€30–€150	€150–€600	Moderate
Throttle learn with diagnostic software (where required)	€0–€0	€30–€80	€30–€80	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.

P0638 on specific vehicles

P0638 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0638 on Opel

Opel Vectra C 2.2 DTI (Y22DTR)

See Opel-specific causes & cost

P0638 on Peugeot

Peugeot 206+ 1.4 petrol (TU3A)

See Peugeot-specific causes & cost

These codes are often seen alongside P0638 or indicate related issues:

Common questions about P0638

What does P0638 mean?: The engine computer is moving the electronic throttle and it is not getting there properly: it lags, or the motor needs far more drive than normal. It is a performance fault, so the wiring may be intact.
Is P0638 the throttle body?: Usually. A dirty plate, worn motor gears or a faulty sensor inside the throttle body cause most cases. A loose or wet connector sets the same code and costs far less to fix, so it is checked first.
Can I drive with P0638?: Only slowly, to the nearest safe place or workshop. Power is normally cut, and because the fault can come and go, the car may lose power again at a bad moment.
Can P0638 come and go?: Yes. A worn position sensor or a loose connector can drop out briefly, so the car loses power and then drives normally after a restart. An intermittent P0638 still needs fixing, because the next drop-out can happen while overtaking.
Will cleaning the throttle body fix P0638?: It can, if carbon makes the plate drag. Clean it with the ignition off, then run the throttle learn. Cleaning does not help worn gears or a faulty sensor, so if the code returns within days the throttle body needs replacing.
How much does it cost to fix P0638?: Cleaning the throttle body with a learn costs roughly 30 to 90 euros. A connector or wiring repair runs 70 to 220 euros, and a new electronic throttle body 150 to 600 euros fitted. Where the learn needs diagnostic software, add 30 to 80 euros.

Read our detailed guides

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