C1657

Code

Generic C — Chassis

Brake Pressure Sensor Circuit Range/Performance

Brand: Generic

Type: C — Chassis

Views: UK: 6 EN: 5 RU: 6

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed sensor wiring harness
Poor connector contact or corrosion at sensor/ECU connector
Faulty brake pressure sensor (internal failure)
Intermittent/open/short to supply or ground
Low system voltage or poor ground at ABS module
Hydraulic problems causing unexpected pressure behavior (leaks, stuck valve, collapsed line)

Symptoms

ABS warning lamp and/or traction control lamp illuminated
Brake warning light may also be present
Diagnostic trouble code(s) stored (C1657 and possibly related codes)
Inconsistent brake pedal feel or unexpected ABS/ESC activation
Loss of normal ABS/ESC function or limited braking performance in some conditions
Recorded live data shows pressure signal out of expected range or jumps erratically

What to check

Retrieve and record freeze-frame and all related codes with a capable scan tool
Visual inspection of sensor, harness, and connectors for damage, corrosion, or loose pins
Check vehicle battery and charging voltage—low voltage can cause false readings
Backprobe sensor connector and measure reference voltage, signal, and ground with key on (follow vehicle service manual)
Compare live sensor output to expected values while applying brake pressure (pedal or hydraulic test rig)
Wiggle harness and connectors while observing live data/scan tool for intermittent changes

Signal parameters

Reference (supply) voltage typically ≈5.0 V — verify vehicle spec before testing
Signal output usually proportional to pressure; many sensors ≈0.5–4.5 V across range (0 to full scale) — check vehicle-specific spec
At rest (no pressure) signal commonly ~0.5–1.0 V; increasing pressure causes rising voltage toward supply rail
Some systems use a frequency or PWM-type pressure sender or report pressure via ABS module over CAN — verify sensor type in service manual
Sensor ground should be near 0.0 V; any significant voltage on ground indicates wiring/ground issue

Diagnostic algorithm

Connect a scan tool, read and record all stored/related DTCs and freeze frame data. Note battery voltage at time of fault.
Visually inspect sensor, harness, and connectors for damage, corrosion, or water ingress. Repair any obvious issues.
With key ON (engine off), backprobe the sensor connector: verify reference (5V) supply, signal output, and ground presence. Compare to vehicle spec.
With a second person applying the brake pedal (or using a hydraulic pressure tool), monitor live sensor output. Confirm signal changes smoothly and proportionally to pressure. Note any sudden jumps, drops, or clamping at rails.
Perform wiggle test on harness and connectors while watching live data to detect intermittent opens or shorts.
If voltage/signal is out of range, isolate by disconnecting sensor and measuring resistance (if applicable) or checking for short to voltage/ground on wiring. Repair short/open as required.
If wiring checks good, swap with a known-good sensor (if available) or bench test sensor per manufacturer procedure. Replace sensor when it fails to meet spec.
If new sensor and wiring are good but code returns, test ABS module inputs and grounds; inspect for internal module faults or communication errors. Consider module replacement or reprogramming only after verifying external circuits good.
After repairs, clear codes and perform a road test including brake activation to confirm the fault does not return. Re-scan to ensure no related codes remain.

Likely causes

Broken/frayed signal or ground wire to pressure sensor
Corroded or water-intruded connector at sensor
Failed pressure sensor element (output out of spec)
Poor ground at chassis or ABS module causing erratic readings
ABS module input circuit fault

Fault status

⚠️ Status

Brake Pressure Sensor Circuit Range/Performance — the pressure sensor output is outside the expected range or behaves inconsistently relative to vehicle/brake input. Inspect sensor, wiring, grounds, and related hydraulic/ABS components.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours