Timing and crank/cam sensorsGeneric OBD-II codeUrgency: As soon as possible
Code P0340: camshaft sensor circuit fault
P0340 means: camshaft position sensor "A" circuit (bank 1 or single sensor).[1][2][3] The ECU has detected a fault in the camshaft position sensor "A" circuit (bank 1 or single sensor): it is not receiving a valid signal telling it where the camshaft is. It uses that data to coordinate ignition timing and fuel injection.[1][2][4]
What code P0340 means
The ECU has detected a fault in the camshaft position sensor "A" circuit (bank 1 or single sensor): it is not receiving a valid signal telling it where the camshaft is. It uses that data to coordinate ignition timing and fuel injection.[1][2][4]
P0340 and P0341 look alike, but they are not the same. P0340 indicates a circuit fault, meaning the sensor signal is missing or faulty. P0341 indicates that the signal arrives but is inconsistent: it is outside the expected range or out of phase with the crankshaft signal.[1][2][5][6][7]
It is a generic OBD-II code (it starts with P0), so it means the same on any make; what changes from one engine to another is the most likely cause.[8]
Original definition (SAE J2012): Camshaft Position Sensor "A" Circuit (Bank 1 or Single Sensor)[1][2][3]
Causes of P0340
From most to least likely, according to the sources.
- 1Faulty or failing camshaft sensor. Carista considers it the most common cause: over time, the internal Hall element degrades from heat.[1][2][4]
- 2Damaged wiring or connector: grounded, short-circuited or worn wires, or a corroded or oil-soaked connector. Carista points out that this is common at the connector next to the timing cover on high-mileage engines.[1][2][3][4]
- 3Dirty or damaged camshaft reluctor ring (tone wheel), producing missing pulses.[2][4]
- 4Worn timing chain or belt (a stretched chain, or one that has jumped a tooth).[2][4]
- 5Faulty or failing crankshaft position sensor.[1]
- 6Engine ECU fault (MechanicBase notes that sometimes it only needs an update).[1][4]
- 7An electrical problem in the starter motor, according to Autodoc Club.[1]
Symptoms
- Engine warning light on.[1][2][4]Engine warning light: faults that cause it
- Hard starting, with the engine cranking for longer than normal before it fires, or a car that will not start.[1][2][3][4]Hard to start: faults that cause it
- The engine stalls unexpectedly, even while driving; it can then be hard to restart.[1][2][3][4]Engine stalls: faults that cause it
- Loss of power and poor acceleration, because the ECU switches to a fallback strategy for fuel and ignition.[1][2][4]Less power: faults that cause it
- Rough running and an unstable idle.[2][4]Vibrations: faults that cause it
- Hesitation when accelerating and misfires.[2][4]Jerking: faults that cause it
- Increased fuel consumption.[4]Uses more fuel: faults that cause it
How to diagnose P0340
In order: from the most likely and cheapest to check to the most expensive.
- 1Read all the codes with a diagnostic tool and see whether there are others (P0335, P0341, P0016, misfires). Then clear the code and check whether it comes back.[4]
- 2Inspect the sensor connector and its wiring: oil, corrosion, broken, chafed or grounded wires.[1][2][3][4]
- 3With the diagnostic tool, compare the camshaft position with the crankshaft position in live data: they should stay in phase.[2]
- 4Test the sensor following the procedure in the service manual (resistance and signal) and check that it is properly secured. Replace it only if the signal is erratic or absent.[2][3][4]
- 5Check the crankshaft position sensor circuit.[1]
- 6If replacing the sensor does not fix it and the wiring is fine, check the camshaft reluctor ring and the condition of the timing chain or belt.[2][4]
- 7Leave the ECU until last: diagnose it and, if necessary, update or replace it.[1][4]
Can I keep driving with P0340?
As soon as possible
The sources agree that this is not a fault to ignore. Autodoc Club considers it a safety hazard, because the car may not start or may start with great difficulty, and urges fixing it immediately to avoid serious engine damage; MechanicBase rates it as serious and advises against driving with it, mainly because of the risk of losing power in the middle of traffic; and Carista gives it a high severity and cites sudden stalling while driving, followed by long cranking before the engine restarts.[1][2][4]
Documented faults related to P0340
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 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.
- 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.
- High severityFrequency: 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 severityFrequency: 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 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.
Timing chain: the most serious faults by engine and car
- Critical severityFrequency: Very frequent1.5 BlueHDiWear and breakage of the 7 mm chain between the camshaftsIn 1.5 BlueHDi engines built between October 2017 and January 2023, the 7 mm chain linking the camshafts can stretch and break, causing serious engine damage. Stellantis has recalled them and covers the fault for 10 years or 240,000 km.Repair (garage): €730–€820
- Critical severityFrequency: Very frequent1.2 and 1.4 TSITiming chain stretch and tensioner failure (EA111)On the 1.2 and 1.4 TSI EA111 (2006-2015) the chain can stretch and the tensioner fall short; if the chain jumps a tooth, the valves hit the pistons. Volkswagen admitted the defect in 2012 and revised the chain and tensioner between 2010 and 2011.Repair (garage): €700–€1,400Appears at around 30,000 km
- Critical severityFrequency: Very frequentBMW N47Rear timing chain stretch and breakageYes: the N47 has its timing chain at the rear of the engine, next to the gearbox, and on a very high proportion of units, especially those built between 2007 and 2009, it stretches or breaks prematurely because of an inadequate tensioner, with a risk of destroying the engine.Repair (garage): €1,590–€3,000Appears at around 50,000 km
- Critical severityFrequency: Very frequentOM651Timing chain stretch and tensioner failureYes: the OM651 timing chain can stretch prematurely, above all on units built up to 2013, and in 2014-2015 Mercedes-Benz recalled around 114,000 vehicles in Germany over a defective sealing ring in the tensioner. A metallic rattle on a cold start is the first sign.Repair (garage): €2,000–€3,500Appears at around 120,000 km
Timing belt: the most serious faults by engine and car
- Critical severityFrequency: Very frequent1.2 PureTechOil-bath timing belt degradationThe oil-bath belt on the 1.2 PureTech (2012-2025) can swell and shed debris that blocks the oil pump pick-up; without lubrication, the engine can be destroyed. Stellantis covers it up to 10 years or 180,000 km and asks for it to be changed every 100,000 km or 6 years.Repair (garage): €400–€800
- Critical severityFrequency: Common1.0 EcoBoostDegradation of the timing belt running in oilYes: the 1.0 EcoBoost's timing belt runs in oil and can degrade over the years, shedding bits of rubber that block the oil pump and seize the engine without warning. The NHTSA is investigating the case in the United States and Ford has shortened the recommended replacement interval.Repair (garage): €800–€1,200
- Critical severityFrequency: Common1.5 / 2.0 EcoBlueDegradation of the wet timing belt (2.0 EcoBlue)Yes: the 2.0 EcoBlue debuted a timing belt that runs bathed in oil on Ford's diesels. Over the years it can degrade and shed debris that affects the lubrication circuit, with a risk of seizure. A roundup by Autopista.es places it in the Focus, Kuga, Transit and Transit/Tourneo Custom.
- Critical severityFrequency: Common1.0 / 1.5 VTEC TurboEngine failure caused by the wet timing beltYes: the 1.0 VTEC Turbo (P10A2) uses an oil-bath timing belt that degrades over time, blocks the lubrication circuit and can destroy the engine completely. Fiches-auto.fr documents several cases in the Honda Civic between 72,000 and 114,000 km.Appears at around 72,000 km
Alternator and starter motor: the most serious faults by engine and car
- High severityFrequency: Occasional2.2 JTDm Multijet IIAlternator cable touching the exhaust gas recirculation pipe (fire risk)An Alfa Romeo campaign covers diesel Stelvio built between 18 January 2017 and 18 September 2018: an alternator cable may rub against the exhaust gas recirculation pipe and cause a short circuit, with a fire risk in the worst case.
- Medium severityFrequency: Occasional1.7 CDTIPremature alternator wearThe Hitachi-brand alternator fitted at the factory to the 1.7 CDTI tends to wear out sooner than expected, according to a German buying guide on the Opel Astra H, with typical replacements at around 140,000 km; there are similar accounts on the Opel Meriva with this engine.
- Critical severityFrequency: OccasionalAlfa Romeo JuniorRisk of electric arcing at the 48 V starter-generator terminal on the hybrid JuniorYes: a March 2026 Safety Gate alert (campaign F60F) covers Junior MHEVs built between 27 November 2023 and 18 December 2025. The clearance between the particulate filter pipe and the 48 V starter-generator terminal cover is under 10 mm and, in damp conditions, there could be electric arcing and fire.
- Critical severityFrequency: OccasionalBMW Serie 3 G202025 campaign for corrosion of the starter motor relay (risk of fire)Yes: in September 2025 BMW recalled, among other models, the 2019 to 2021 330i (G20) because the starter motor relay can corrode, overheat and cause a short circuit with a risk of fire even when the car is parked.
P0340 by make
Documented faults that can trigger P0340 in each make's engines and cars.
Frequently asked questions
Can I drive with code P0340?
The sources advise against it: the car may start badly or stall while driving, and the lack of power when accelerating is dangerous in traffic. Autodoc Club calls it a safety hazard and urges fixing it immediately; MechanicBase recommends not driving with this code.[1][4]
What is the difference between P0340 and P0341?
Both refer to camshaft sensor "A" on bank 1, but they describe different faults. P0340 is a circuit fault: the ECU cannot see the camshaft position because the signal is missing or faulty, and it points mainly to the sensor, the connector or the wiring. P0341 indicates that the signal exists but is not consistent: it is out of range or out of phase with the crankshaft signal, and it means looking at mechanical causes too, such as the reluctor ring or a stretched or jumped timing chain or belt.[1][2][5][6][7]
Do you have to replace the camshaft sensor when P0340 appears?
Not necessarily. MechanicBase warns that many technicians and DIYers replace the sensor straight away, but that there are other causes that do not require it; the first step is to check the connector and the wiring. Carista adds that if replacing the sensor does not solve the problem, you need to check the reluctor ring and timing chain stretch.[2][4]
Can P0340 leave the car unable to start?
Yes. According to Autodoc Club and MechanicBase, it can cause hard starting or prevent starting altogether; Carista cites sudden stalling with long cranking to get it going again, and Saab's workshop documentation lists stalling and failure to start as symptoms of this code.[1][2][3][4]
Does P0340 mean the same on all makes?
Yes. Codes that start with P0 are generic OBD-II codes and have the same definition across all manufacturers.[8]
Will I pass the MOT with code P0340?
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.[9]
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.
- Código OBD2 P0340: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
- P0340: OBD-II code P0340 flags a fault in the camshaft position sensor circuitCarista · Technical documentation · consulted 2 October 2026
- DTC P0340 Camshaft position sensor "A" circuit (bank 1 or single sensor), Saab 9-2X (9346) 2005, 2.5iSaab WIS Online (Saab Workshop Information System) · Technical documentation · consulted 2 October 2026
- What Does The P0340 Code Mean?Mechanic Base · Technical documentation · consulted 2 October 2026
- Código OBD2 P0341: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
- P0341: OBD-II code P0341 means the camshaft position sensor signal is present but implausibleCarista · Technical documentation · consulted 2 October 2026
- P0341 - Camshaft Position Sensor Circuit Range/PerformanceSamarins.com · Technical documentation · consulted 2 October 2026
- On-board diagnosticsWikipedia · Other source · consulted 2 October 2026
- 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