AutoCodes – Jeep – P1266 Jeep

P1266 Jeep Code - Glow Plug #4 Circuit

Quick Answer

The glow plugs are used to preheat the combustion chambers in order to achieve the ignition temperature required for the fuel-air mixture. Common causes include Faulty Glow Plug #4, Glow Plug #4 harness is open or shorted, Glow Plug #4 circuit poor electrical connection. 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: P1266 Jeep indicates Glow Plug #4 Circuit.
Common causes: Common causes include Faulty Glow Plug #4, Glow Plug #4 harness is open or shorted, Glow Plug #4 circuit poor electrical connection.
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 2,359

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 Jul 02, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P1266 Jeep Description

The glow plugs are used to preheat the combustion chambers in order to achieve the ignition temperature required for the fuel-air mixture.
The glow plug consists of a housing with a female thread and an interference-fit rod. The heating element is integrated into the glow rod. It consists of a heating winding and a control winding connected in series.
When the glow plug system is switched "ON", a current of about 30 ampere flows to each glow plug. The heating winding heats the glow plug. The control winding increases its resistance as the temperature rises and limits the current to approximately 15-25 ampere. The glow plug is protected this way from overloads.

OBDII Code P1266 Jeep - Glow Plug #4 Circuit - AutoCodes.com — P1266 Jeep Code - Glow Plug #4 Circuit

What does this mean?

What are the Possible Causes of the DTC P1266 Jeep?

Faulty Glow Plug #4
Glow Plug #4 harness is open or shorted
Glow Plug #4 circuit poor electrical connection
Faulty Glow Plug Controller

How to Fix the DTC P1266 Jeep?

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 does this mean?

Code Tech Notes

Good information on how to inspect, remove and replaced the glow plugs: Jeep Glow Plug Inspection, Remove and Replace

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1266 Jeep 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.