Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1978 BMW 633CSi Automatic TransFACTORY OEM SERVICE PROCEDURE
EGR System
- After 25, 000 miles an EGR service warning light will light up, to indicate that the filter of the EGR system should be replaced and the thermal reactor(s) should be inspected for cracks or other damage. After replacing filter and checking thermal reactor(s), the mileage interval switch must be reset.
- The switch is connected to speedometer cable, on left side engine carrier. Two contacts are located in the switch, one is marked "REAC" (reactor) and the other "EGR". The appropriate contact must be pushed inwards to extinguish the warning lamp and reset the mileage recorder to zero.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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