[SOLVED] P128A Code – Fixing Intermittent/Erratic Cylinder Head Temperature Sensor Circuit

If you see the automobile fault code P128A and your engine light is on, it’s important not to ignore it. This code usually indicates a problem with the thermostat or the Cylinder Head Temperature (CHT) sensor.

The symptoms can vary, but the most common one is the engine overheating.

The cause could be a wrong thermostat, the engine not operating within the correct temperature range, low engine coolant level, or a faulty CHT sensor. To fix this issue, you should visually inspect the wiring harness and connectors, checking for any damage or poor electrical connections.

It’s also essential to look for broken, bent, pushed out, or corroded connector pins. The repair time for this problem is estimated to be around 1.0 hour.

Don’t delay in addressing this fault code to prevent further damage to your vehicle.

Repair Importance Level10.0 (Out of 10)
Estimated Repair TimeApproximately 1.0 hour
Repair Difficulty Level10.0 (Out of 10)

When the engine light is on or the service engine soon warning light is illuminated, it could be a sign of the p128a fault code.

  • The symptoms of the automobile fault code P128A include the Engine Light being ON or the Service Engine Soon Warning Light being illuminated.

The automobile fault code P128A can be caused by various factors, including a wrong thermostat, engine overheating, low coolant level, and faulty CHT sensor or its related components.

  • The fault code P128A can be caused by: a wrong thermostat, the engine not operating within the correct temperature range, engine overheating, low engine coolant level, a faulty Cylinder Head Temperature (CHT) sensor, an open or shorted CHT sensor harness, or a poor electrical connection in the CHT sensor circuit.

To fix fault code p128a, start by visually inspecting the wiring harness, connectors, and components for any damage or corrosion.

  • To fix the automobile fault code P128A, you need to follow these steps: 1.
  • Check the possible causes mentioned above.
  • 2.
  • Visually inspect the wiring harness and connectors related to the fault code.
  • 3.
  • Look for any damaged components.
  • 4.
  • Check for broken, bent, pushed out, or corroded pins in the connectors.
  • 5.
  • Repairing this fault code is estimated to take approximately 1.0 hour.

The automobile fault code P128A can be diagnosed and fixed within an estimated repair time of 1.0 hour.

The cost of the repair will depend on the hourly rate charged by the auto repair shop, which typically ranges between $75 and $150 per hour.

The P128A fault code refers to the Cylinder Head Temperature (CHT) Sensor Circuit IntermittentErra.

This sensor is located in the cylinder head and is responsible for sending a signal to the Powertrain Control Module (PCM) to indicate the temperature of the cylinder head. When the temperature exceeds 126°C (-258°F), the PCM disables four fuel injectors at a time.

This is done to prevent further overheating and damage to the engine. The PCM alternates which four injectors are disabled every 32 engine cycles.

The remaining four cylinders that are not being fuel injected act as air pumps to help cool the engine.

If the temperature continues to rise and exceeds 154°C (310°F), the PCM will disable all of the fuel injectors until the engine temperature drops below 154°C (310°F). This is a safety measure to protect the engine from severe overheating.

If you encounter the P128A fault code, it is important to have the Cylinder Head Temperature Sensor and its circuit checked for any intermittent or erroneous readings. This will ensure that the engine is properly cooled and prevent any potential damage.

What are the possible causes of the automobile fault code P128A?

If you’re seeing the engine light on or the service engine soon warning light, the fault code P128A might be the culprit. This code can be caused by a variety of issues, including a wrong thermostat, the engine not operating within the correct temperature range, engine overheating, low engine coolant level, a faulty Cylinder Head Temperature (CHT) sensor, an open or shorted CHT sensor harness, or a poor electrical connection in the CHT sensor circuit. To fix this, start by visually inspecting the wiring harness and connectors, checking for any damage or corrosion. Also, look out for broken, bent, pushed out, or corroded connector pins.

How can I visually inspect the wiring harness and connectors to fix the P128A fault code?

If you’re dealing with the P128A fault code and your engine light is on, it’s time to take action. The cause could be a wrong thermostat, engine not operating within the correct range, engine overheating, low engine coolant level, faulty Cylinder Head Temperature (CHT) sensor, or an open or shorted CHT sensor harness. To fix this issue, start by visually inspecting the wiring harness and connectors. Look for any damaged components and check for broken, bent, pushed out, or corroded connector pins. Don’t forget to also check the other possible causes listed above.

What should I look for when checking for damaged components or corroded connector pins to resolve the P128A fault code?

If you’re dealing with the P128A fault code and your engine light is on, there are a few things you should check. The cause could be a wrong thermostat, the engine not operating within the correct range, engine overheating, low engine coolant level, a faulty Cylinder Head Temperature (CHT) sensor, or an open or shorted CHT sensor harness. To fix the issue, visually inspect the wiring harness and connectors. Look for any damaged components and check for broken, bent, pushed out, or corroded connector pins.

p128a error fault code explained

If your engine light is on and you’re experiencing issues with your thermostat, engine overheating, low coolant level, or faulty CHT sensor, it’s time to take action.

Start by visually inspecting the wiring harness and connectors, checking for any damage or corrosion.

Look out for broken or bent pins as well.

Don’t delay, address these possible causes now.

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