AutoCodes – Infiniti – P1126 Infiniti

P1126 Infiniti Code - Thermostat Function

Quick Answer

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long enough. Common causes include Low engine coolant level, Faulty Thermostat, Leakage from sealing portion of thermostat. 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: P1126 Infiniti indicates Thermostat Function.
Common causes: Common causes include Low engine coolant level, Faulty Thermostat, Leakage from sealing portion of thermostat.
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 9,595

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Apr 26, 2019

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P1126 Infiniti Description

Engine coolant temperature has not risen enough to open the thermostat even though the engine has run long enough. This is due to a leak in the seal or the thermostat open stuck.

Thermostat Function is for 2000-2001 Infiniti models.

OBDII Code P1126 Infiniti - Thermostat Function - AutoCodes.com — P1126 Infiniti Code - Thermostat Function

What does this mean?

What are the Possible Causes of the DTC P1126 Infiniti?

Low engine coolant level
Faulty Thermostat
Leakage from sealing portion of thermostat
Engine coolant temperature sensor

How to Fix the DTC P1126 Infiniti?

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

If no coolant leaks are present, replacing the thermostat usually takes care of the problem.

For Infiniti vehicles other than the 2000-2001 models see: P1126 Infiniti

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1126 Infiniti 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.

Need more information about the P1126 Infiniti code?

Need more information on how to fix the P1126 Infiniti code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1126 Infiniti code diagnosed by a professional: Find a repair shop in your area

Information for Specific Infiniti Models

P1126 2000 Infiniti G20 — Thermostat Function
P1126 2001 Infiniti G20 — Thermostat Function
P1126 2002 Infiniti G20 — Thermostat Function
P1126 2003 Infiniti G35 — Throttle Control Motor Relay Circuit Open
P1126 2004 Infiniti G35 — Throttle Control Motor Relay Circuit Open
P1126 2005 Infiniti G35 — Throttle Control Motor Relay Circuit Open
P1126 2000 Infiniti I30 — Thermostat Function
P1126 2001 Infiniti I30 — Thermostat Function

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.

Frequently Asked Questions about P1126 Infiniti Code

1. What does the OBDII code P1126 mean for an Infiniti?

P1126 indicates a Thermostat Function issue, meaning the engine control module (ECM) has detected a problem with the operation of the thermostat.

2. What are the common symptoms of a P1126 code?

Symptoms may include engine overheating or running cooler than expected, poor fuel efficiency, and the check engine light being illuminated.

3. What causes the P1126 code to appear?

Common causes include a stuck-closed or stuck-open thermostat, low coolant levels, a malfunctioning coolant temperature sensor, or wiring/electrical issues.

4. Can I keep driving with a P1126 code?

It is not recommended to drive with this code for an extended period, as improper thermostat function can lead to engine overheating or inefficient performance.

5. How is the P1126 code diagnosed?

A mechanic will typically check the thermostat for proper operation, inspect the coolant level, look for leaks, and test the coolant temperature sensor and related wiring.

6. How do I fix the P1126 code on my Infiniti?

Repairs may include replacing the thermostat, refilling or flushing the coolant, repairing wiring or connectors, or replacing the coolant temperature sensor.

7. How much does it cost to fix a P1126 code?

The cost to repair a P1126 code varies but typically ranges between $150 and $300 for thermostat replacement, depending on labor rates and parts pricing.

8. Can a low coolant level trigger the P1126 code?

Yes, a low coolant level can cause improper thermostat function, which may result in the P1126 code being triggered.

9. Will clearing the P1126 code fix the problem?

Clearing the code may turn off the check engine light temporarily, but the underlying issue must be addressed to prevent the code from returning.

10. How can I prevent a P1126 code in the future?

Regularly check and maintain proper coolant levels, ensure the cooling system is flushed on schedule, and replace the thermostat as needed to prevent issues.