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 850 2.5 Siemens P1275339 S103955403H
Vendors's code: P1275339
Product code: P1275339
Barcode:
Code 39:
ISBN:
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Engine control unit Volvo 850 2.5 Siemens P1275339 S103955403H
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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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P1275339 engine ECU for your Volvo 850 2.5 – how to check the fit
We offer a used, fully working Siemens engine control unit with part numbers P1275339 and S103955403H. It fits if the same numbers appear on the label of the ECU in your car. Available locked or unlocked.
Engine control unit Volvo 850 2.5 Siemens P1275339 S103955403H
This used Siemens P1275339 engine computer for the Volvo 850 2.5 processes sensor signals and calculates the engine’s operating parameters.
ECU markings
- P1275339 – Volvo part number
- S103955403H – Siemens number
You will find the numbers on the casing of your current ECU. A similar-looking unit will not necessarily fit – the full number is what counts.
When the ECU may be faulty
- the engine will not start despite a good power and fuel supply,
- no communication with the ECU during diagnostics,
- limp mode with no sensor fault,
- damage after water ingress or a voltage spike.
Rule out the battery, fuses and connectors first – they are often the real cause.
Locked or unlocked?
There are two variants: locked, with the previous vehicle’s data and immobiliser, for garages, and unlocked, which we prepare before dispatch.
Not every unlocking method is possible for every ECU – it depends on the number, the software and the car’s immobiliser. Before ordering the unlocked version, ask us about the options for the P1275339 ECU.
All variants are described on our Locked & Unlocked ECUs page.
Questions and answers
| Is S103955403H the same ECU as P1275339? |
|---|
| Yes. Both numbers appear on the label of the same ECU. |
| Will the ECU start the engine straight after fitting? |
| The locked version will not – it needs programming and matching to the immobiliser. With the unlocked version it depends on the preparation method, which we agree before purchase. |
| 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. |
Not sure which variant to choose? Email contact@auto24parts.com with the numbers from your label – we will check the available options.
