Fuel injection system faults (VW Sharan 1)

The VR6 engine ECU has a built-in fault recorder that detects faults in the operation of the ECU and Motronic system components and enters them into the ECU memory. If the coolant temperature sensor, intake air temperature sensor, or air flow meter potentiometer are faulty, the ECU begins to operate according to the values accepted by default. After the ECU returns to normal mode, the use of the values accepted by default ceases. If the detected fault has been eliminated by itself, then after the fiftieth engine start, information about this fault will be erased from the fault recorder memory.

To facilitate troubleshooting, it is possible to request current parameters via the ECU and activate one or another element of the system.

To search for faults entered into the ECU memory device, it is necessary to use diagnostic stands of the company that manufactured the car. After the faults are eliminated at the service station, they are erased from the fault recorder memory, which allows the fault recorder to record new faults when they are detected, without confusing them with old faults.

Cause of malfunction	Method of elimination
Cold engine does not start or starts with great difficulty
1. Blown fuses #15 and #18	1. Replace
2. The relay responsible for voltage is faulty	2. Check at the service station
3. The fuel pump is faulty (the engine is not getting enough fuel)	3. Repair the pump or replace it with a new one (a special key will be required for repairs)
4. The fuel pressure regulator is faulty	4. Have the pressure regulator checked at a service station
5. Coolant temperature sensor is faulty	5. Check the temperature sensor with an ohmmeter
6. Throttle actuator is faulty	6. Conduct a check at a service station
7. The ECU is faulty	7. Have it checked at a service station
8. The wires between the Hall sensor and the ECU are broken	8. Check and repair
9. The engine sucks in air through leaky connections or damaged hoses	9. Check all hose connections located on or leading to the air filter housing
Warm engine does not start or starts with great difficulty
1. The vacuum line leading to the fuel pressure regulator is leaking	1. Check. Perform all the specified checks
2. Leaky injectors	2. Check them at a service station
The engine starts and then stalls again
1. The throttle actuator is faulty	1. Conduct a check at a service station
2. The vacuum line leading to the fuel pressure regulator is leaking	2. Check
3. The lambda probe is faulty	3. Conduct a check at a service station
The engine vibrates heavily at idle
1. The voltage supply relay or coolant temperature sensor is faulty	1. Check it yourself or at a service station
The engine stalls
1. The fuel filter is clogged	1. Install a new filter
2. The fuel pump is faulty (the engine is not getting enough fuel)	2. Repair the pump or replace it with a new one (a special key will be required for repairs)
3. Leaky injectors	3. Check them at a service station
4. Throttle actuator is faulty	4. Conduct a check at a service station

The original can be seen on the portal: VWmanual.ru