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P1299 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Definition

P1299 is an OBD-II Code that refers to Cylinder Head Temperature Sensor Detected Engine Overheating Condition

Meaning

A P1299 code is a manufacturer specific code usually either in Ford or Lincoln vehicles caused by an ECM (Engine Control Module) receiving a signal that the engine’s cylinder head temperature sensor has detected an engine overheating condition.

The most common reason for this is a faulty thermostat or low engine coolant or multiple other factors. A code is stored when the computer senses that there is an abnormal signal coming from the cylinder head temperature (CHT) sensor. The CHT sensor reads the temperature of the engine’s cylinder head and sends a signal to the ECM (engine control module) of the engine.

Causes

Common causes for this code include:

  • Short or open wiring for cylinder head temperature sensor
  • Broken thermostat
  • Low engine coolant
  • Bad cylinder head temperature sensor

Symptoms

The symptoms of a P1299 code are:

  • MIL (Malfunction Indicator Lamp) illumination
  • Check Engine light, 
  • Rough idling, 
  • Misfires in multiple cylinders
  • Excessive heat from engine
  • Engine stalling when at idle or driving under load
  • An overall lack of power/performance

Diagnosis

To diagnose a P1299 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Test the engine coolant temperature circuit for continuity.
  3. Inspect leaks
  4. Locate and inspect all wiring harnesses for loose or broken connectors or bad splices.
  5. Replace any malfunctioning parts such as sensors, relay, control module, etc..

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P1299 code:

  • Not verifying that all engine wiring harnesses are properly connected.
  • Not properly identifying the cause of the problem when using Freeze Frame Data.
  • Assuming that a part is good without actually testing it out.
  • Replacing parts without knowing what they do or how they work together.
  • Improperly reading and interpreting Sensor tests.

How serious is this?

A P1299 code is not very serious in most cases, however it is crucial that the cause of the problem is diagnosed in order to prevent further damage. If an engine overheats, severe internal damage can occur in a short amount of time.

What repairs can fix the code?

The following are solutions that may fix this problem:

  • Refilling of engine coolant
  • Replace CHT sensor
  • Repair or replacement of Faulty wiring to CHT sensor
  • Repair or replacement of open or shorted CHT sensor

Related codes

A P1299 is related to and may be accompanied by the following codes:

P0016 – Cylinder Head Temperature Sensor Circuit Malfunction

P0017 – Cylinder Head Temperature Sensor Circuit Range/Performance Problem

P0018 – Cylinder Head Temperature Sensor Circuit Low Input

P0019 – Cylinder Head Temperature Sensor Circuit High Input

Conclusion

In conclusion, the P1299 code is a manufacturer specific trouble code that means that the engine’s cylinder head temperature sensor has detected an overheating condition. There are several causes for this, such as a faulty thermostat, low coolant level or other problems. If this code is ignored and not diagnosed properly it can cause severe internal damage to the engine and possibly leave you stranded far from home or even cause your engine to catch on fire.