OBD Guide

P18C4

Gear Position Sensor Circuit 1 Low Voltage

P18C4 is an OBD-II diagnostic trouble code meaning: Gear Position Sensor Circuit 1 Low Voltage. Common causes: open or short circuit in the sensor circuit, gear position sensor malfunction. Estimated repair cost: $17–56.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–56 (est.)

Symptoms

  • Incorrect gear shifting
  • Transmission of the gearbox into emergency mode
  • Check Engine Light Illuminates
  • Reduced engine performance
  • Problems starting the engine

Causes

  • Open or short circuit in the sensor circuit
  • Gear position sensor malfunction
  • Connector problems or contact corrosion
  • Malfunction of the transmission control unit
  • Problems with power or grounding of the circuit

How to Fix

  1. Check the integrity of wiring and connectors
  2. Check the voltage in the sensor circuit
  3. Replace the gear position sensor if necessary
  4. Check and, if necessary, replace the transmission control unit
  5. Clean contacts and eliminate corrosion

Related codes

FAQ

What does the P18C4 code mean?

P18C4 is an OBD-II diagnostic trouble code that indicates: Gear Position Sensor Circuit 1 Low Voltage

What causes a P18C4 error code?

The most common causes of P18C4 include: Open or short circuit in the sensor circuit; Gear position sensor malfunction; Connector problems or contact corrosion; Malfunction of the transmission control unit.

How do I fix a P18C4 diagnostic trouble code?

To fix P18C4: Check the integrity of wiring and connectors. Check the voltage in the sensor circuit. Replace the gear position sensor if necessary. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P18C4?

Yes, but get it checked soon

How much does it cost to fix P18C4?

The estimated repair cost for P18C4 is $17–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat