AutoCodes – Lincoln – P128A Lincoln

P128A Lincoln Code - Cylinder Head Temperature Sensor Circuit Intermittent/Erratic

Quick Answer

The Cylinder Head Temperature (CHT) Sensor is mounted into the wall of the cylinder head and is not connected to any coolant passages. Common causes include Wrong thermostat, Not at operating range, Engine overheated. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P128A Lincoln indicates Cylinder Head Temperature Sensor Circuit Intermittent/Erratic.
Common causes: Common causes include Wrong thermostat, Not at operating range, Engine overheated.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 2,859

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 30, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P128A Lincoln Description

The Cylinder Head Temperature (CHT) Sensor is mounted into the wall of the cylinder head and is not connected to any coolant passages. The CHT sends a signal to the Powertrain Control Module (PCM) indicating the cylinder head temperature. If the temperature exceeds 126°C (-258°F), the PCM disables four fuel injectors at a time. The PCM will alternate which four injectors are disabled every 32 engine cycles. The four cylinders that are not being fuel injected act as air pumps to aid in cooling the engine. If the temperature exceeds 154 °C (310°F), the PCM disables all of the fuel injectors until the engine temperature drops below 154°C (310°F).

OBDII Code P128A Lincoln - Cylinder Head Temperature Sensor Circuit Intermittent/Erratic - AutoCodes.com — P128A Lincoln Code - Cylinder Head Temperature Sensor Circuit Intermittent/Erratic

What does this mean?

What are the Possible Causes of the DTC P128A Lincoln?

Wrong thermostat
Not at operating range
Engine overheated
Low engine coolant level
Faulty Cylinder Head Temperature (CHT) sensor
Cylinder Head Temperature (CHT) sensor harness is open or shorted
Cylinder Head Temperature (CHT) sensor circuit poor electrical connection

How to Fix the DTC P128A Lincoln?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P128A Lincoln code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.