AutoCodes – Generic – P027F

P027F Code - Cold Start Air Fuel Ratio Control System Command Rich

Quick Answer

The cold start emission reduction strategy controls air-fuel ratio to lean when the engine is started at cold conditions to lower the emission while the catalyst is not warmed up enough. Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control Module 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: P027F indicates Cold Start Air Fuel Ratio Control System Command Rich.
Common causes: Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control Module 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 1,968

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 Aug 16, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P027F Description

The cold start emission reduction strategy controls air-fuel ratio to lean when the engine is started at cold conditions to lower the emission while the catalyst is not warmed up enough. If the commanded air-fuel ratio is too lean or too rich compared to the target air-fuel ratio, the Powertrain Control Module (PCM) detects a malfunction and stores a Diagnostic Trouble Code (DTC).

OBDII Code P027F - Cold Start Air Fuel Ratio Control System Command Rich - AutoCodes.com — P027F Code - Cold Start Air Fuel Ratio Control System Command Rich

What does this mean?

What are the Possible Causes of the DTC P027F?

Faulty Powertrain Control Module (PCM)
Powertrain Control Module harness is open or shorted
Powertrain Control Module circuit poor electrical connection

How to Fix the DTC P027F?

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 P027F 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 P027F code?

Need more information on how to fix the P027F code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P027F code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P027F Acura — Cold Start Air Fuel Ratio Control System Command Rich
P027F Honda — Cold Start Air Fuel Ratio Control System Command Rich

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 P027F Code

1. What does the OBDII code P027F mean?

P027F indicates a problem with the Cold Start Air-Fuel Ratio Control System, where the system is commanding a rich air-fuel mixture beyond expected limits during cold starts.

2. What are the common symptoms of code P027F?

Symptoms may include difficulty starting the engine in cold weather, rough idling during cold starts, increased fuel consumption, and black smoke from the exhaust.

3. What causes the P027F code to appear?

Common causes include a faulty engine coolant temperature sensor, issues with the air-fuel ratio sensors, a malfunctioning fuel injector, or incorrect PCM programming.

4. Can I drive my vehicle with code P027F?

While the vehicle may still be drivable, prolonged driving with this code can lead to reduced fuel efficiency, engine damage, or catalytic converter issues. Prompt diagnosis and repair are recommended.

5. How do I fix the P027F code?

Repairs may involve replacing a faulty coolant temperature sensor, cleaning or replacing air-fuel ratio sensors, inspecting fuel injectors for clogs or leaks, or reprogramming the PCM.

6. How is code P027F diagnosed?

Mechanics use an OBDII scanner to confirm the code, inspect sensor data during cold starts, test the coolant temperature sensor, and check the fuel system for abnormalities.

7. Can a dirty air filter cause code P027F?

Yes, a dirty air filter can restrict airflow, which may lead to improper air-fuel ratios during cold starts and potentially trigger this code.

8. Will resetting the code clear the issue?

Resetting the code may temporarily clear the warning, but the underlying issue must be fixed to prevent the code from returning.

9. How much does it cost to repair a P027F code?

Repair costs vary depending on the cause but typically range from $100 to $500, including parts and labor for sensor or injector replacements.

10. Can a bad oxygen sensor trigger code P027F?

Yes, a malfunctioning oxygen or air-fuel ratio sensor can provide incorrect readings, causing the PCM to command a richer mixture than necessary during cold starts.