B0521

Tachometer Signal Circuit Malfunction

Severity

⚠️ Medium

Can you drive?

Limited driving only, diagnose soon

Approx. repair cost

$56–167 (est.)

Symptoms

Tachometer does not work
Floating idle speed
The engine may stall

Causes

Broken or damaged tachometer circuit wires
Tachometer malfunction
Problems with the crankshaft speed sensor
Corrosion or poor contact in connectors
ECU malfunction

How to Fix

Check the integrity of the tachometer circuit wiring
Check contacts in connectors
Check crankshaft speed sensor
Check the serviceability of the tachometer
If necessary, replace faulty components

Related codes

P0335 P0336 P0650