| Important: Required procedure prior to opening high-pressure injection system |
Caution | The injection system consists of a high-pressure section (maximum approx. 140 bar) and a low-pressure section (approx. 7 bar). |
| Prior to opening the high-pressure section (e.g. when removing the high-pressure pump, fuel rail, injectors, fuel pipes or fuel pressure sender -G247-), the fuel pressure in the high-pressure section must be reduced to a specified level. The procedure is described below. |
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| Special tools and workshop equipment required |
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| Vehicle diagnostic tester |
| Reducing fuel pressure in high-pressure section |
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| Connect a vehicle diagnostic tester. |
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| Start engine and run at idling speed. |
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| Select „Engine electronics“ in vehicle self-diagnosis. |
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| Then select „Basic setting“. |
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| Select „Reducing fuel pressure in fuel rail“ from the list. |
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| Then select „Measured values“. |
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| Observe fuel pressure displayed on tester. |
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| Fuel pressure will drop to a specified value. |
WARNING | There is a risk of injury: avoid skin contact with fuel. |
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| Wear safety goggles and protective clothing when opening the fuel system. |
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| Before opening the high-pressure section of the fuel system, place a clean cloth around the connection to catch escaping fuel. |
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| The high-pressure system must be opened »immediately« after reducing the fuel pressure; wrap a clean cloth around the connection. Catch the escaping fuel. |
Note | The pressure will increase again due to the effect of residual heat if the high-pressure system is not opened immediately. |
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| Using a vehicle diagnostic tester, erase event memory and generate readiness code in engine control unit in „Guided Functions“ mode. |
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