P0340 - camshaft sensor error

Error p0340 is defined as — Camshaft Position Sensor A Circuit. It can occur for a variety of reasons — when the camshaft sensor fails, malfunctions in its wiring, problems in the work of the engine control (ECU). The error itself is not critical, and the car can be used when it is formed.

However, some inconveniences occur — increased fuel consumption, reduced power and so on. To eliminate the reasons why the error code p0340 was formed is not difficult, and most car owners can cope with it.

How and why the engine changes its behavior

Сamshaft position sensor

The primary function of this device is to determine the position of the camshaft at a specific point in time.

The relevant information is transmitted to the electronic engine control unit (ECU) so that it calculates the fuel injection timing from each injector programmatically.

If its operation is disturbed, the ECU automatically enters the emergency mode, which provides pair-parallel injection instead of phased injection. This results in excessive fuel consumption and loss of engine power.

Signs of an error

There are a number of indications that a problem with the camshaft position sensor or its wiring can be detected. The situations described below may also indicate other malfunctions, therefore additional diagnostic scan with an error scanner is required.

DTC P0340 will cause:

• Problem starting the engine. Often, the error p0340 leads to the fact that the car simply does not start. And it can be both when the engine is cold and warmed up. However, most often it is expressed simply in the fact that you have to twist the starter longer when starting the engine. Naturally, it negatively affects the condition of the car battery, and its entire electrical system as a whole.
• Unstable idle engine speed. In some cases, the car simply stalls at idle speed, so the engine must be forcibly maintained by pressing the accelerator pedal.
• The engine is «tromping». That is, ignition skips are observed in the cylinders. This leads to a loss of power and changes in the sound of the engine.
• Decrease in the dynamic characteristics of the car. It is expressed in the fact that the car poorly accelerates, poorly picks up engine speed, there may be a «sag» pedal, that is, after pressing the accelerator pedal acceleration begins in a few seconds. The car may also have poor uphill performance, especially if it is loaded.
• Fuel consumption increases by 10 to 20 per cent. This situation occurs due to the fact that the electronic control unit switches to the emergency fuel supply mode, i.e. in pair-parallel mode. Accordingly, all the advantages of the phased injection are leveled.
• Check Engine warning light is activated on the dashboard. At its activation, it is always necessary to perform an error scan. If the above signs of failure are not observed, but the scanner still gives error code p0340.

It is worth noting that the listed changes in the behavior of the car are not so relevant for engines running on gasoline. Their power loss and increased fuel consumption are not as great as in diesel engines or those working with gas equipment.

Conditions of error p0340 formation

P0340 Camshaft Position Sensor A Bank 1: video

These conditions may differ in different electronic control units in different cars. However, in most cases, the following factors are necessary for the formation of the p0340 error signal:

• no signals are received from the camshaft sensor for more than 5 seconds of starter rotation;
• the signals from the camshaft sensor are not received by the ECU at engine speed of 600 rpm or more.

In some cars, this error is formed not in one trip, but in three trips. However, in this case, diagnosis will be difficult.

Causes of the error

The are only three main causes of engine error p0340:

1. Damage of the camshaft sensor wiring. In particular, we are talking about its breakage. As a rule, the camshaft sensor has three wires — power, «mass» and signal. Due to certain mechanical damages, they can be frayed, and the signal will stop going through them. Most often this happens at the terminals or at the contacts (so called «chips», connected to the sensor or connectors of the electronic control unit). Another option is damage to the insulation, which causes them to be shorted to the chassis or between themselves. The result of such failure will be sending incorrect data to the ECU.
2. Damaged camshaft sensor. The camshaft sensor is a simple and reliable device, and it rarely fails. However, if error code p0340 is generated, it makes sense to check the camshaft sensor.
3. ECU malfunction. This is a rare case, because when the electronic control unit partially fails, not only p0340 errors will be observed, but also many others. However, such a situation is possible.

Sometimes the cause of error p0340 is not strong enough fixing when you replace it yourself (low tightening torque, which can make the sensor vibrate while driving) or large gap between the working (sensitive) part of the sensor and a tooth on the indicator wheel, located on the camshaft.

How to get rid of error p0340

Methods of fixing depend on the causes of their occurrence, as well as the specific model of cars — for example, «Nissan», «Ford», «Chevrolet», «Opel», «Toyota» or others. However, the general algorithm for checking will be as follows:

1. Right cylinder head
2. Camshaft position sensor
3. Elec. connector
4. Mounting bolt

1. Check the latch, which provides a hard contact fixing the chip to the body of the sensor. In some situations, it may be broken off, and this leads to loss of contact between all or separate wires and contacts on the sensor.
2. Check the quality of installation of the sensor in its seat. In particular, check the tightening torque of the nut (usually the sensor is fixed with a bolt with a nut with a diameter of 10 mm or similar, depending on the particular engine). Make sure that the sensor suitable for the particular engine is installed in the engine. In particular, not only by mounting, but also by model, because sensors can differ both geometrical shape and dimensions, and because of this the sensitive element of the sensor will not register passage near its tooth, which will lead to absence of corresponding signals to ECU. If the sensor is unsuitable — it is necessary to buy a new camshaft sensor and replace it.
3. Visually check condition of contacts and terminals in electrical scheme of camshaft sensor connection. In some cases there is oxidation (rust) on the responsible terminals, which leads to a decrease in contact quality. This is due to exposure to moisture and/or simply from old age. If oxides are found, they must be removed by thoroughly wiping the contacts. Special electrical contact cleaners can be used to clean difficult soiling.
4. Using a multimeter turned on in the test mode or measuring the insulation resistance, check the integrity of the wires coming from the ECU to the camshaft sensor. Usually there are three wires. Besides checking the continuity of wires, you should also check the insulation resistance value in pairs between them, as well as between each of the wires and the car chassis («mass»). In the latter case, however, the earth wire will be «ringing» with the chassis. And in the process of the described test, the multimeter probes should be placed on the contacts of the corresponding connectors. When checking the insulation resistance value, you need to know clearly which connector on the «chip» is responsible for what.


Camshaft Position Sensor Circuit High Input — Code P0343: video

5. If the check of the wires shows that they have defects (breakage, insulation damage), it is necessary to perform a visual inspection in order to determine the location of their damage. First of all, you must pay attention to the places of bends and breaks, where wires change their shape and can be simply rubbed as a result of vibration. You should also look to see if the wires are passing through areas where moisture or process fluids (such as grease) have accumulated. Over time, in these places the insulation can be damaged. If you can not find the place of damage — then you need to replace the camshaft position sensor wiring completely. It is necessary to use special flexible car wires with the appropriate cross section of the core.
6. If all is normal with wires and connector, you should check the condition of the sensor itself.
7. If there are no problems with the camshaft sensor as well — it is necessary to check normal operation of the electronic control unit. However, it is not recommended to do it yourself, because it is a complex and responsible part of the car. Therefore, for help it is necessary to apply to the car service, where there are specialists and additional diagnostic equipment.

Finally, if the camshaft sensor is malfunctioning, it makes sense to check the crankshaft sensor operation, since these shafts work synchronously, and if there is no signal from the camshaft sensor, the ECU uses signals from the crankshaft sensor. It is necessary to check if there are no errors in ECU memory concerning crankshaft sensor, for example P0335, and also if possible to inspect its mechanical condition and wiring (similarly as for camshaft position sensor).