A faulty transmission control module (TCM) most often causes limp mode with the gearbox stuck in one gear, harsh jolts when you select D or R, erratic gear changes, flashing PRND letters and a gearbox or engine warning light. However, the same symptoms are often caused by a low gearbox oil level, a weak battery, a poor earth or a faulty sensor. To test a transmission control module, start by checking the battery and reading the fault codes with a diagnostic tool that can talk to the gearbox control unit, then check the power supply, the connector, the oil and the live data. Below we explain the symptoms, the diagnostic steps and what the most common fault codes mean.
Engine Control Unit Volkswagen Polo 1.2 Siemens 03D906032C 5WP4012403
Vendors's code: 5WP4012403
Product code: 5WP4012403
Barcode:
Code 39:
ISBN:
Select a product option:
Individual variants may differ in price
product option
Important: Depending on the ECU type and vehicle model, not all of the options listed below may be available.
To select the correct option for your vehicle and ECU, please contact us before purchasing:
contact@auto24parts.com
1. Locked
This option is intended for professional workshops with the required specialist equipment and technical knowledge.
The ECU has been removed from a vehicle intended for recycling and still contains the immobilizer data and other information from the previous vehicle. Before it can be used in another car, it must be unlocked and then programmed using specialist automotive diagnostic equipment.
2. Unlocked
Several preparation methods may be available. The possible options depend on the ECU type, vehicle model and immobilizer system. Please contact us before purchasing, as some preparation methods are not available for every ECU.
Our electronics specialists can prepare the ECU in one of the following ways:
a) ECU with PIN code (Car Pass)
The PIN code is supplied, but programming with a suitable diagnostic tool is still required. After installing the ECU, it must be reset using the supplied PIN code and then programmed to the vehicle’s immobilizer system.
b) VIRGIN ECU
The data from the previous vehicle is removed and the ECU is restored to a clean, factory-like state. After installation, it must be programmed to the vehicle using a compatible specialist diagnostic tool. Unless another preparation method is specified in the product description, this is the standard unlocking option for most of our ECUs.
c) Plug & Play – IMMO OFF
The immobilizer function is disabled in the ECU. After installation, the engine can start without additional immobilizer programming. Please note that the vehicle will no longer have an active immobilizer function, and an immobilizer warning light or fault code may remain, depending on the vehicle model.
d) Plug & Play – Automatic Programming
After installation, the ECU automatically learns and saves the required vehicle data. No additional programming is normally required.
e) Plug & Play – 1:1 Clone
The data from your original ECU is copied to another fully functional ECU. The cloned unit is then ready for installation without additional programming.
You must send us your original ECU so that we can transfer its data to the replacement unit.
The original ECU must have working communication with the vehicle, a diagnostic tool or our programming equipment. If the required data cannot be read, a complete 1:1 clone may not be possible.
3. Complete Plug & Play Set
A complete matched set containing the ECU, immobilizer components and all other parts required to start the vehicle without additional programming. All components supplied in the set must be installed in the vehicle.
Important:
Dispatch time depends on the selected option. If an unlocked or specially prepared version is ordered, the preparation service usually requires an additional 1–2 business days.
Ask about the product
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Price 30 euros applies shipments to 5 kg on worldwide. Above this weight, please contact us by email to check price
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What does the number 03D906032C on the ECU sticker mean?
It is the Volkswagen part number for the Siemens 5WP4012403 engine control unit from a Polo 1.2 petrol. The letter C at the end indicates the module version, which we sell used and working.
Engine Control Unit Volkswagen Polo 1.2 Siemens 03D906032C 5WP4012403
The 03D906032C ECU comes from a Volkswagen Polo with a 1.2 petrol engine and was made by Siemens. The number 5WP4012403 is the designation given by Siemens. The module oversees fuel injection, ignition and idle speed – a fault in it can often be felt at the very first attempt to start the engine.
Markings on the casing
- 03D906032C – Volkswagen (VW) part number
- 5WP4012403 – Siemens number
When matching, stick to the number 03D906032C including the letter C. A version with a different letter is a different software or hardware variant.
Typical failure symptoms
- the engine will not start, even though the starter turns and fuel is getting through,
- the engine warning light is on and the memory holds injection or ignition faults with no component failure,
- the diagnostic tester cannot connect to the ECU,
- the engine stalls or idles unevenly.
The first step should be reading the fault codes and checking the wiring – many faults lie in the cables, not in the module.
Locked or unlocked – which to choose?
The 03D906032C ECU can be ordered locked or unlocked. The locked version holds the data and immobiliser of the car it came from – your workshop then carries out the unlocking, programming and adaptation.
With the unlocked version we take care of the preparation and do it before dispatch (usually 1–2 working days). Bear in mind that whether a PIN / CAR PASS, Virgin version, IMMO OFF, auto programming or a clone can be used depends on the number, software and immobiliser – write to us before buying. See also ECU preparation options.
Questions and answers
| Can I fit an ECU with a different letter at the end of the number? |
|---|
| We do not recommend it without checking with us. The letter indicates the software or hardware version, so the safest choice is a module with an identical VW number. |
| How long does it take to prepare the unlocked version? |
| Usually 1–2 working days before dispatch. Beforehand we confirm which unlocking method is possible for this unit. |
| Are 5WP4012403 and 03D906032C the same ECU? |
| Yes, they are two numbers of one module: 03D906032C is the VW number and 5WP4012403 is the Siemens number. |
| Is the module working and covered by a warranty? |
| Yes – the ECU is used, working and in good condition. You will find the warranty period in the product features table. |
We will help you choose the version – just send a message to contact@auto24parts.com with the numbers from the label.