Mercedes-Benz W201 (190, 190E and 190D 1982–1993): common faults, maintenance guides and repair tips.
The most common causes are the solder joints and fuses of the overvoltage protection relay (YJ relay) behind the battery, low charging voltage, the br...
Remove the fuses one at a time and measure the current with an ammeter. When the drain stops as a particular fuse is removed, the fault is in that cir...
A typical fault is the fuel pump relay: the solder joints on its circuit board crack, so the pump gets no power even though the relay clicks. The symp...
On the petrol model the fan is controlled by an electric magnetic clutch. The clutch is switched on by a two-pin temperature sensor at the front of th...
The potentiometer tells the control unit the position of the air flap plate. When its track wears or gets dirty, the voltage fluctuates and the car je...
Most commonly from the seals and hoses, so frayed O-rings and the drier often need replacing. Sensitive points also include the compressor shaft, evap...
Yes. The rubber boot under the injection unit cracks with age and lets extra air into the engine. It upsets the idle and can stall the engine. The boo...
The timing chain often lasts hundreds of thousands of kilometres, so replacing it preventively is not always necessary. Its condition is found by meas...
Throttle return relies on two springs, one of which is on the throttle body under the injection unit. A broken spring leaves the pedal movement loose ...
Typical signs are coolant disappearing without a visible leak and white smoke at start-up. Home test: run the engine warm, switch off, wait two minute...
1. Raise the rear of the car, supported, and remove one wheel bolt. 2. Turn the adjuster wheel through the bolt hole with a screwdriver until the shoe...
The position of the roof is adjusted with the adjusting screws (8 mm) on the rails. Hold the roof by hand in the correct position while tightening the...
Check fuse 12 first. Remove it completely, since just twisting it is not always enough, and also check the fuse's contact end. Next listen to the vacu...
On the 722.4 automatic the kickdown is electric: it is activated by a pressure switch under the accelerator pedal, not by a cable. Check the switch wi...
Often the injector gets no electricity. The cause may be weak solder joints in the overvoltage protection relay (YJ relay) behind the battery or a blo...
The most common cause is a clogged heater core or its hoses, so hot coolant does not circulate. The blockage can be limescale. Another possibility is ...
Usually from the heater core or the seals of its pipes. If the liquid tastes sweet, it is antifreeze. The heater core often leaks on the W201. The lea...
Check fuse number 1 (red, 16 A) first. An oxidised fuse can look intact, so replace it with a new one. If the fuse is fine, the cause may be a worn ig...
The sensor is at the front of the cylinder head, near the thermostat housing, and it has two or four pins. It tells both the fuel injection and the ig...
Measure the voltage at the battery terminals with the engine running. The correct value is about 13.8–14.4 V. The battery's resting voltage with the e...
The idle control valve bypasses the throttle and lets air into the intake manifold for idling. The control unit adjusts how far it opens according to ...
The most common cause is the instrument lighting dimmer, which can be dirty, oxidised or have loose solder joints. Other causes are a loose or oxidise...
Usually the tensioner's shock absorber or its mounting is worn. The mounting hole at the lower end of the damper easily wears oval, so it moves and ra...
Hydraulic valve lifters can tap after starting, when oil has not yet filled them. The noise usually stops as the engine warms up or after a few hundre...
According to the owner's manual, the minimum idle pressure of a warm petrol engine is 0.3 bar. For example, 1–1.5 bar is plenty. When cold the pressur...
The source of the noise is often the propshaft support bearing or its rubber, a wheel bearing, or worn gear contact in the rear end (differential). Th...
The most common causes are a clogged fuel filter, clogged small screens in the injector outlets of the fuel distributor and a faulty pressure regulato...
Lubricate the linkage before replacing parts. Stop the wipers at the upper corner of the glass, open the plastic cover and grease the sliding piece of...
Common causes are a rear caliper fitted the wrong way round, a stuck piston in the caliper and a faulty master cylinder. The caliper's bleed screw mus...
The cause is usually broken or fatigued rear springs, which may be missing coils. A worn spring pad can also cause a low rear end. In the worst case t...
The aluminium-cased overvoltage protection relay (YJ relay) is found behind the battery, behind a plastic cover. If it does not work, cold-start enric...