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Home >> Volvo >> 2000 >> S40 L4-1.9L Turbo VIN 25 B4204T2 >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Component Tests and General Diagnostics >> Checking Engine Speed (RPM) Sensor Interference
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Checking Engine Speed (RPM) Sensor Interference






Checking engine speed (RPM) sensor interference

Checking engine speed (RPM) sensor interference




The engine speed (RPM) sensor is sensitive to interference from surrounding power cables, for example the starter motor cable, or similar cables with high amperage. This occurs when starting the engine for example.
Interference can cause difficulty in starting the engine, the engine does not start at all, the tachometer flickers at start attempts etc.
Causes of interference can be:
- surrounding power cables, for example a faulty routed starter motor cable
- incorrectly routed transmission bolted joints for the engine.

Checking the power cable
Check for incorrectly routed power cables (routed too close to the engine speed (RPM) sensor).

Checking the bolted joints
When removing and installing the transmission it is important that all the bolts for the engine are correctly tightened. Incorrectly tightened bolts can cause poor ground connection and interfere with the engine speed (RPM) sensor. Check that all the bolts from the transmission to the engine are correctly tightened.
Remedy as necessary

Continue - DONE

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