What does it mean?
P1571 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Traction Control System - PWM Circuit No Frequency .
Symptoms
- Check engine light on together with the ABS and traction control warning lamps
- Traction control is completely inactive, so wheelspin is not reduced on wet or loose surfaces
- No engine torque reduction when a wheel loses grip, which matters most in poor weather
- Cruise control may also be disabled because it relies on the same data
- Stability control functions unavailable and the vehicle feels less secure on slippery roads
- Engine performance itself is usually unchanged
Likely causes
- Open circuit in the signal wire between the ABS or traction control unit and the engine control module
- Blown fuse or missing supply voltage to the traction control unit, so it never transmits
- Corroded, wet or unlatched connector at either module
- Poor ground on the ABS or traction control module
- Faulty wheel speed sensor or a stored ABS fault that has shut the traction function down
- Harness damage where it passes through the bulkhead or along a chassis rail
- Internal failure of the traction control unit output stage
How to fix it
- Scan the ABS and traction control module for its own codes before working on the engine side
- Check the fuses and measure supply voltage and ground at the traction control unit
- Inspect both module connectors for corrosion, moisture and pushed-back terminals
- Use an oscilloscope or a duty cycle capable meter on the signal line to see whether any waveform is present
- Test the signal wire for continuity between the two modules and for shorts to ground
- Diagnose and repair any wheel speed sensor faults, since these can silence the traction output
- Repair the harness or replace the traction control unit last, then verify that the warning lamps go out and traction control operates