What Does C1420 Mean?
The ABS/stability control module has detected a short-to-battery voltage condition in the hydraulic fluid pressure or flow sensor circuit. This sensor monitors the hydraulic pump and brake fluid pressure within the ABS/traction control system. With this fault, the module cannot accurately monitor hydraulic system status, and the ABS or stability control system may be disabled.
Common Causes
35%
Wiring harness damage allowing pressure sensor circuit to contact a power wire
25%
Hydraulic pressure sensor internal failure with voltage backfeed
20%
Connector pin damage or corrosion causing cross-contact with power pin
10%
Previous improper wiring repair cross-feeding voltage into sensor circuit
10%
ABS control module internal failure on sensor input circuit
Diagnostic Steps
1
Disconnect the ABS HCU connector. Measure voltage on the hydraulic pressure/flow sensor circuit pins with a voltmeter referenced to ground — should read 0V. Any voltage indicates a backfeed from another source.
2
If voltage is present, disconnect the pressure sensor connector and re-check at both harness ends to isolate whether the short is in the harness, sensor, or module.
3
Inspect the wiring harness from the sensor to the ABS module, looking for chafing against the ABS pump motor power wires or relay output wires that run in close proximity.
4
Examine the ABS HCU multi-pin connector for bent, spread, or corroded pins. The pressure sensor pins often sit adjacent to pump motor power pins, making cross-contact a common failure mode.
5
If no external wiring fault is found, test the pressure sensor by measuring its output voltage with a known-good 5V reference supply — output should vary proportionally with applied pressure and not show battery voltage.
Estimated Repair Cost
$200 - $1,200
Parts + labor, varies by vehicle and location
The ABS/stability control module has detected a short-to-battery voltage condition in the hydraulic fluid pressure or flow sensor circuit. This sensor monitors the hydraulic pump and brake fluid pressure within the ABS/traction control system. With this fault, the module cannot accurately monitor hy...
The most common cause of C1420 (Hydraulic Fluid Pressure/ Flow Circuit Short to Vbatt) is: Wiring harness damage allowing pressure sensor circuit to contact a power wire
Typical repair costs for C1420 range from $200 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS and/or stability control may be partially or fully disabled because the module cannot verify hydraulic system pressure. Normal manual braking still works, but electronic brake assistance is unreliable. Drive conservatively and avoid situations requiring emergency braking. Have this repaired promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1420 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS / Traction Control
Difficulty
Type
Manufacturer
Recommended Tools
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