OBD Guide

P1A77

Starter/Generator Control Module Coolant Temperature Sensor 2 Circuit High Voltage

P1A77 is an OBD-II diagnostic trouble code meaning: Starter/Generator Control Module Coolant Temperature Sensor 2 Circuit High Voltage. Common causes: malfunction of coolant temperature sensor no. 2, open or damaged sensor circuit. Estimated repair cost: $17–78.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–78 (est.)

Symptoms

  • Check Engine Light Is On
  • Reduced efficiency of the regenerative braking system
  • Problems starting the engine
  • Decreased hybrid battery charge
  • System transition to emergency operation mode

Causes

  • Malfunction of coolant temperature sensor No. 2
  • Open or damaged sensor circuit
  • Short circuit in the sensor circuit
  • Corrosion of electrical contacts
  • Starter/Generator Control Module Malfunction

How to Fix

  1. Check the temperature sensor readings with a scanner
  2. Inspect the sensor wiring harness and connectors for damage.
  3. Check the integrity of the sensor circuit
  4. Measure the resistance of the temperature sensor
  5. If necessary, replace the coolant temperature sensor

Related codes

FAQ

What does the P1A77 code mean?

P1A77 is an OBD-II diagnostic trouble code that indicates: Starter/Generator Control Module Coolant Temperature Sensor 2 Circuit High Voltage

What causes a P1A77 error code?

The most common causes of P1A77 include: Malfunction of coolant temperature sensor No. 2; Open or damaged sensor circuit; Short circuit in the sensor circuit; Corrosion of electrical contacts.

How do I fix a P1A77 diagnostic trouble code?

To fix P1A77: Check the temperature sensor readings with a scanner. Inspect the sensor wiring harness and connectors for damage.. Check the integrity of the sensor circuit. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P1A77?

Yes, but get it checked soon

How much does it cost to fix P1A77?

The estimated repair cost for P1A77 is $17–78. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat