Mercedes Coupes/Sedans/Wagons 1974-1984 Repair Guide

1978-79 Vehicles

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The emission control system for 1978-79 models is very similar in components and operation to the 1977 version.

230 MODELS



See Figure 1

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Fig. Fig. 1: Emission control component locations1977-79 230 models

Perform the following tests in the order given with the engine at idle at normal operating temperature.

Testing the System

Refer to the 1977 230 model procedures for "Testing the System."

280E, 280CE & 280SE (FEDERAL) MODELS



See Figure 2

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Fig. Fig. 2: Emission control component locations1977-79 280E, CE and SE models (Federal)

Perform the following tests in the order given with the engine at normal operating temperature and idling.

Testing the System

Refer to the 1977 280E and 280SE (Federal) model procedures for "Testing the System."

280E, 280CE & 280SE MODELS (CALIFORNIA)



See Figure 3

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Fig. Fig. 3: Emission control component locations1977-79 280E, CE and SE models (California)

Perform the following tests in the order given with the engine at idle and at normal operating temperature.

Testing the System

Refer to the procedures under "Testing the System" for 1977 280E and 280SE California models.

450SEL, 450SL & 450SLC MODELS (FEDERAL)



See Figure 4

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Fig. Fig. 4: Emission control component locations1977-80 4.5L V8 models (Federal)

Perform the following tests in the order given with the engine idling at normal operating temperature.

Testing the System

Refer to the procedures for "Testing the System" under 1977 450SL, 450SLC, 450SEL (Federal) models.

450SEL, 450SL, 450SLC (CALIFORNIA) & 6.9 MODELS



See Figures 5 and 6

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Fig. Fig. 5: Emission control component locations1977-80 4.5L V8 models (California)



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Fig. Fig. 6: Emission control component locations1978 6.9 models

Perform the following tests in the order given with the engine idling at normal operating temperature.

Testing the System

Refer to the procedures for "Testing the System" under 1977 450SL, 450SLC, 450SEL (California) and 6.9 models.

CATALYST REPLACEMENT WARNING INDICATOR



A warning light in the instrument cluster comes on at 37,500 mile intervals, indicating that the catalyst should be replaced. The catalyst mileage counter is located under the dash and is driven by the speedometer cable. To reset the mileage counter, push the reset pin on the counter.

 
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