Air intakeGeneric OBD-II codeUrgency: Garage soon
Code P0638: electronic throttle: control out of range (bank 1)
P0638 means: throttle actuator control, bank 1: out of range or performance problem.[1][2] The ECU has detected that the electronic throttle actuator ("drive-by-wire" system) is not behaving as expected: either it does not act according to the operating conditions, or the actual position does not match the one it commanded. "Bank 1" only matters on V engines; on the rest it is the only throttle.[2][3]
What code P0638 means
The ECU has detected that the electronic throttle actuator ("drive-by-wire" system) is not behaving as expected: either it does not act according to the operating conditions, or the actual position does not match the one it commanded. "Bank 1" only matters on V engines; on the rest it is the only throttle.[2][3]
It is a generic OBD-II code (it starts with P0), so it means the same on any make.[1]
Original definition (SAE J2012): Throttle Actuator Control Range/Performance (Bank 1)[1][2]
Causes of P0638
From most to least likely, according to the sources.
- 1Faulty or worn throttle actuator (in which the position potentiometer is usually built in).[2][3]
- 2Damaged, burnt, shorted or corroded wiring and connectors in the actuator or position sensor circuit.[2]
- 3CAN network problems not directly related to the throttle, according to TroubleCodes.net.[2]
- 4An ECU remap with unauthorised parameters can trigger this and other codes. The ECU itself is a rare cause.[2]
Symptoms
- Warning light on; in some cars the code spends several cycles as pending before the light comes on.[2]Engine warning light: faults that cause it
- Poor acceleration, hesitation or jerking when accelerating.[2]Less power: faults that cause it
- Hard or impossible starting, sometimes only cold or only warm.[2]Hard to start: faults that cause it
- Uneven or fluctuating idle and stalling at low revs.[2]Engine stalls: faults that cause it
How to diagnose P0638
In order: from the most likely and cheapest to check to the most expensive.
- 1Note down the codes and the freeze-frame data. Even if only P0638 shows up, there may be CAN network codes that a basic reader does not display.[2]
- 2Inspect the throttle actuator's wiring and connectors, and check its supply and ground.[2][3]
- 3Use a diagnostic tool to check the operation of the actuator and its position sensor, and clean the throttle if it is dirty.[2][3]
- 4If it persists, go to a garage with specific equipment. CarWiki says that in many cases the actuator is built into the throttle and is not replaced separately.[2][3]
Can I keep driving with P0638?
Garage soon
With a faulty electronic throttle the car may have limited response, stall at low revs or not start, so get it checked soon. TroubleCodes.net insists on investigating the code even if it appears only as pending.[2]
Documented faults related to P0638
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Accelerator pedal: the most serious faults by engine and car
- High severityFrequency: Rare1.0 VVT-i2010 recall for the accelerator pedalIn January 2010 Toyota recalled, as part of a worldwide campaign, the Aygo, Peugeot 107 and Citroën C1 built between February 2005 and August 2009 because of an accelerator pedal that could stay partly depressed or return slowly to idle.
- Critical severityFrequency: OccasionalMercedes-Benz GLE V167Accelerator pedal mounting plate that bends and releases the pedalThe plate that holds the accelerator pedal module can bend and release the pedal from the body; the pedal can then stay pressed down, prevent kickdown or obstruct the brake pedal. It affected 882 GLE models built between 3 and 17 May 2023.
- High severityFrequency: OccasionalToyota Aygo IAccelerator pedal slow to return on the Toyota Aygo (2010 campaign)In January 2010, Wikipedia records a Toyota recall over the accelerator pedal, which could return slowly to idle; it covered the Aygo, 107 and C1 built between February 2005 and August 2009, although it was later clarified that it only affected the automatic Aygo.
Engine sensors: the most serious faults by engine and car
- High severityFrequency: Occasional2.0 DTI and 2.2 DTIVP44 injection pump and air mass meter failureGerman Wikipedia documents recurring failures of the Bosch VP44 injection pump and the air mass meter in the early years of this engine. An owner testimony for this engine describes the pump being replaced at 192,500 km, at a cost the owner calls «prohibitive».
- Medium severityFrequency: Common2.0 TDIClogged particulate filter or faulty pressure sensorThe 2.0 TDI's particulate filter clogs if the car mostly makes short journeys, because it never gets to regenerate; sometimes the fault is just the differential pressure sensor. Cleaning it costs around €200 and replacing it, €800 to €3,000.Repair (garage): €800–€3,000
- Medium severityFrequency: Common1.4 and 1.6 8vCrankshaft position sensor failure (TDC sensor)The crankshaft position sensor (capteur PMH, or TDC sensor) appears repeatedly in the reliability sources for the Clio II, the Kangoo I and the Dacia Logan I with this engine, with hard cold starting or stalling as the main symptoms. It is a cheap part, but the failure can leave you stranded.
- Medium severityFrequency: Common1.4 and 1.6 16vCrankshaft position sensor failureThe crankshaft position sensor (capteur PMH) appears repeatedly in the reliability sources for almost every generation with this engine, with hard cold starting, stalling or the car cutting out unexpectedly. It is a cheap part, but the failure can leave you stranded.
Wiring, connectors and short circuits: the most serious faults by engine and car
- Critical severityFrequency: OccasionalBMW N62 / N63Additional turbo coolant pump with a risk of short circuit and fireIn 2011 BMW recalled 5, 6 and 7 Series, X5 and X6 models built between 2007 and 2011 because of the additional turbo coolant pump: moisture, a short circuit and, in extreme cases, a fire. In 2012 there was another campaign for a crack in the pump, with a more robust version.
- Critical severityFrequency: Occasional1.6 GDi híbrido (Kappa)Main relay of the power relay assembly (overheating and fire risk)Yes, on the first units: Hyundai and Kia recalled 2016–2018 Ioniq and Niro hybrids and plug-in hybrids because the main relay that connects the high-voltage battery could come loose, overheat and, in the worst case, cause a fire.
- Critical severityFrequency: Occasional1.6 GDi híbrido (Kappa)Clutch hydraulic actuator (HCA): leak or moisture with risk of short circuit and fireYes, this is the most documented hybrid system fault: the hydraulic actuator that engages the combustion engine with the hybrid assembly has had two recalls (2018 for a leak on the Niro and 2025 for moisture in its electronic board on the Niro, Ceed and XCeed PHEV), with a risk of short circuit and fire.
- High severityFrequency: Occasional1.3 TCeBlown fuel pump fuseOn the Renault Captur II and Clio V with the 1.3 TCe engine, a 20-amp fuse can blow and leave the car without an engine. According to L'argus, in April 2021 this fault still had no factory fix; the official service centre's diagnosis includes checking, and sometimes replacing, the catalytic converter.
- Critical severityFrequency: CommonRover 75Seat SRS connector fault with airbag and seatbelt warning light onAuto Express warns that the Rover 75's seat SRS connector can cause the airbags to fail, and dealers were fixing it with revised connectors. The Dutch APK inspection puts the airbag or seatbelt fault warning among the most frequent defects across almost all series.
- Critical severityFrequency: OccasionalAlfa Romeo GiuliettaShort circuit from badly routed wiring that can prevent gear shifting (KBA campaign, 2010-2015)Yes: according to Germany's KBA, on Alfa Romeo Giulietta cars built between 2010 and 2015 inadequate cable routing could cause a short circuit and, as a result, gear-shift failure.
Frequently asked questions
Can I drive with code P0638?
It is not advisable: there may be erratic throttle response, stalling or hard starting. The sensible thing is to have it checked as soon as possible.[2]
Does P0638 mean the throttle has to be replaced?
Not always. First check the wiring, supply and grounds, and rule out CAN network faults. If the actuator is faulty, the whole throttle assembly is usually replaced.[2][3]
What is "bank 1"?
The bank that contains cylinder 1 on engines with two cylinder heads (V engines). On single-head engines it has no practical relevance.[2][3]
Will I pass the MOT with code P0638?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[4]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- P0638 DTCDTCSearch · Technical documentation · consulted 29 October 2026
- P0638 trouble codeTroubleCodes.net · Technical documentation · consulted 29 October 2026
- OBD Fehlercode P0638CarWiki · Technical documentation · consulted 29 October 2026 · in German
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish