Air intakeGeneric OBD-II codeUrgency: Garage soon
Code P2138: throttle sensors D and E: signals do not correlate
P2138 means: throttle/pedal position sensor/switch "D" and "E" voltage correlation.[1] Cars with an electronic throttle do not rely on a single sensor: according to Wikipedia, the pedal has two or more independent sensors, and HELLA explains that the pedal sensor gives two signals for safety. The control unit compares the two signals with each other and, if they do not have the expected correlation, it cannot verify the actual throttle position. This is what P2138 indicates, and it affects sensors "D" and "E".[1][2][3]
What code P2138 means
Cars with an electronic throttle do not rely on a single sensor: according to Wikipedia, the pedal has two or more independent sensors, and HELLA explains that the pedal sensor gives two signals for safety. The control unit compares the two signals with each other and, if they do not have the expected correlation, it cannot verify the actual throttle position. This is what P2138 indicates, and it affects sensors "D" and "E".[1][2][3]
When it triggers, the control unit turns on the warning light and limits the throttle response to just under half opening, according to CarParts. It is a form of limp mode, in which, according to Wikipedia, the signal to the throttle motor is cut and springs leave it at a raised idle.[1][2]
It is a generic OBD-II code (those starting with P2 are defined by SAE), not specific to a make, so its definition is the same on any car; what changes from one engine to another is the most likely cause.[4]
Original definition (SAE J2012): Throttle/Pedal Position Sensor/Switch D/E Voltage Correlation[1]
Causes of P2138
From most to least likely, according to the sources.
- 1Faulty throttle position (TP) or pedal (APP) sensor. HELLA adds that the fault may lie in the evaluation electronics of the pedal sensor itself.[1][3]
- 2Problems in the circuit: damaged wires or bad connections, or a lack of power or earth at the sensor.[1][3]
- 3Control unit software that needs an update.[1]
- 4Low voltage in the electrical system: a battery disconnection or voltage drops below 10 V.[1]
Symptoms
- Engine warning light on in the instrument cluster.[1][3]Engine warning light: faults that cause it
- Loss or lack of power: the throttle response is limited to just under half opening.[1]Less power: faults that cause it
- The engine may stall when coming to a stop.[1]Engine stalls: faults that cause it
- The car stays in limp mode, with reduced power.[1][3]Limp mode: faults that cause it
- Idle speed higher than normal or a car that does not respond when you press the pedal: HELLA lists these among the symptoms of a faulty pedal sensor in general.[3]
How to diagnose P2138
In order: from the most likely and cheapest to check to the most expensive.
- 1Read all the stored codes with diagnostic equipment and see whether there are others from the pedal and throttle sensors: CarParts lists P2135, P2136, P2137, P2139 and P2140 as related.[1]
- 2Check the battery and the charging voltage, and whether the battery was disconnected recently: CarParts includes battery disconnection and drops below 10 V among the causes.[1]
- 3Check the pedal and its wiring: mechanical damage, damaged wires, loose connectors and the sensor's power and earth. HELLA then proposes measurements with an oscilloscope and multimeter while the pedal is pressed and released, and recommends that two people carry them out.[1][3]
- 4Ask the garage whether there is a control unit software update for this code.[1]
- 5Only when everything above is fine, replace the sensor or the pedal. CarParts warns that P2138 can have many causes and that an experienced mechanic is usually needed to pinpoint the exact one.[1]
Can I keep driving with P2138?
Garage soon
CarParts does not expressly say whether you can drive with P2138, but power limited to just under half throttle opening and the possible stalling of the engine when stopping reduce safety while driving. It is best to drive only as far as the garage, and carefully.[1]
Documented faults related to P2138
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
Engine sensors: the most serious faults by engine and car
- High severityOccasionalFrequency: 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 severityCommonFrequency: 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 severityCommonFrequency: 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 severityCommonFrequency: 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 severityOccasionalFrequency: 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.
- High severityOccasionalFrequency: 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.
- High severityOccasionalFrequency: OccasionalM264/M254Poorly tightened 48 V earth wiring in the mild-hybrid system (fire risk)Mercedes-Benz has issued several recalls (2022-2025) because the 12 V and 48 V earth connections of some cars with a 48 V system may be poorly tightened: resistance rises, the connection heats up and a fire cannot be ruled out. The official workshop checks them and repairs them if necessary in an hour or more.
- High severityOccasionalFrequency: Occasional1.9 TDIUnit injector tappet wear and injector wiring damageOn the unit injector system, the tappets that operate the injectors can wear if the oil is not changed on time, and the injector wiring can be damaged by contact with oil, causing misfires or loss of power.
- Critical severityOccasionalFrequency: 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.
- Critical severityOccasionalFrequency: OccasionalAudi A4 B9Risk of short circuit and fire due to moisture in electrical componentsAudi recalled A4 B9 units built between May 2017 and March 2020 because moisture can seep into an electrical component and cause a short circuit, with a risk of the vehicle catching fire.Repair: €0
Accelerator pedal: the most serious faults by engine and car
- High severityRareFrequency: 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.
- High severityOccasionalFrequency: 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.
- Critical severityRareFrequency: RareToyota Auris IThe accelerator pedal can stick fully down because of condensationToyota issued a recall in Europe (January 2010) on several models, including the Auris, because the accelerator pedal mechanism could accumulate condensation in cold weather and stick or return very slowly to idle, with a risk of unintended acceleration. The campaign covered Auris cars built between October 2006 and January 2010.
Frequently asked questions
What does code P2138 mean?
The control unit has found that the signals from the two pedal or throttle position sensors "D" and "E" do not have the expected correlation with each other, and so it cannot verify the actual throttle position. As a result, it limits the throttle response and turns on the warning light.[1][3]
Can I drive with code P2138?
The sources do not say clearly. Power is limited to just under half throttle opening and the engine may stall when stopping, so the sensible thing is to drive only as far as the garage, and carefully.[1]
Why does the car have so little power with P2138?
Because the control unit cannot trust the throttle position and limits its response to just under half opening, as a protection. In limp mode, according to Wikipedia, the throttle is left at a raised idle that is enough to engage a gear but not dangerous.[1][2]
Can P2138 appear because of the battery?
Yes. CarParts includes a battery disconnection and voltage drops below 10 V among the causes, so it is best to check the condition of the battery and the charging before replacing parts.[1]
Does P2138 mean the same on all makes?
Yes. Generic OBD-II codes defined by SAE, such as those starting with P2, have the same definition across all manufacturers.[4]
Will I pass the MOT with code P2138?
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.[5]
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.
- 1.P2138 Code: Throttle/Pedal Position Sensor/Switch D/E Voltage CorrelationCarParts.com · Technical documentation · consulted 4 October 2026
- 2.Electronic throttle controlWikipedia · Other source · consulted 4 October 2026
- 3.Accelerator pedal sensor – function & designHELLA Tech World · Manufacturer · consulted 4 October 2026
- 4.On-board diagnosticsWikipedia · Other source · consulted 4 October 2026
- 5.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