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1993 Volvo 850 GLT
Fuel (line) filter
The fuel line filter is located next to the fuel pump. This filter is to be changed every 60,000 miles
(96,000 km). The filter is replaced as one complete unit.
Replace more frequently if contaminated fuel is introduced into the tank (or if there is reason to suspect
that this has occurred).
Timing gear belt
Volvo recommends that the timing gear belt be replaced at 50,000 miles (80,000 km) intervals. The first
replacement is at 50,000 miles (80,000 km).
Exhaust Gas Recirculation (EGR)
This system operates by returning some of the exhaust gases to the engine to be recombusted since this
lowers the combustion temperature and the amount of nitrogen oxides released into the atmosphere is
reduced.
The EGR valve should be inspected at 60,000 miles (96,000 km) and thereafter cleaned every 20,000
miles (32,000 km).
pg. 8:8 Servicing (cont.)
Fuel System
The fuel system is all-electronic and is microprocessor-controlled. It can continually compensate for
variation in engine load, speed and temperature to give the best economy and power. A mass air sensor
or a pressure meter on certain models, measures the inducted air. In this way the system can make
instantaneous adjustments for changes in air temperature or density, thus always assuring the best
economy with the lowest possible exhaust emissions.
Heated oxygen sensor
This is an emission control system designed to reduce emissions and improve fuel economy. The heated
oxygen sensor monitors the composition of the exhaust gases leaving the engine. The exhaust gas
analysis is fed into an electronic module. This adjusts the air-fuel ratio to provide optimum conditions
for combustion and efficient reduction of the three major pollutants (hydrocarbons, carbon monoxide
and nitrous gases) by a three-way catalytic converter.
Pulsed Secondary Air Injection (certain models)
This system adds air to the hot exhaust gases as they are expelled from the engine. This causes a
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