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 Volvo V50, S40 30729274A
Vendors's code: B371
Product code: B371
Barcode:
Code 39:
ISBN:
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Engine control unit Volvo V50, S40 30729274A
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30729274A engine ECU for your Volvo V50, S40 – how to check the fit
We offer a used, fully working engine control unit with part numbers 30729274A and B371. It fits if the same numbers appear on the label of the ECU in your car. Available locked or unlocked.
Engine control unit Volvo V50, S40 30729274A
The module 30729274A controls the engine – it reads sensor data and uses it to regulate the fuel system. It is a part for the Volvo V50, S40.
ECU markings
- 30729274A – Volvo part number
- B371 – additional marking
Compare them with the sticker on the ECU in your car. The number decides the fit, not the model alone – Volvo used different ECU versions.
Symptoms of a faulty engine ECU
- the starter cranks but the engine does not fire,
- the diagnostic tool cannot connect to the ECU,
- an engine warning light and fault codes that remain after replacing sensors,
- signs of moisture or corrosion on the connectors or circuit board.
Before replacing the ECU, check the power supply, earths and wiring loom – a damaged wire or connector can cause similar symptoms.
Locked or unlocked?
A locked ECU holds the data and immobiliser of the previous car – it is chosen by garages that will program it themselves. The unlocked version is prepared by us before dispatch.
The available unlocking methods depend on the ECU number and the immobiliser system, so before buying ask what we can prepare for the 30729274A unit.
All variants are described on our Locked & Unlocked ECUs page.
Questions and answers
| What details should I send before ordering? |
|---|
| All the numbers from the label of your current ECU, or a clear photo of it. Based on that, we will check the fit and the possible variants. |
| Can I fit an ECU with a different number suffix? |
| A different suffix can mean a different software or hardware version. Send us a photo of the label and we will check whether the 30729274A ECU is suitable. |
| What condition is the ECU in? |
| It is a used part, fully working and in good condition. The warranty period is shown in the product features table. |
Any questions? Send a photo of your ECU label to contact@auto24parts.com – we will tell you whether this unit will fit.
