Fix P014C: Mechanic’s solutions that WORKED

The code P014C: O2 Sensor Slow Response – Rich to Lean (Bank 1, Sensor 1) indicates a delayed response from the oxygen sensor when transitioning from a rich to lean condition. This can be due to various reasons, including a faulty sensor, exhaust leaks, or issues with the vehicle’s fuel system.

P014C quick overview

Meaning	P014C: O2 Sensor Slow Response – Rich to Lean (Bank 1, Sensor 1)
Is it serious?	Yes, it can lead to increased emissions, reduced fuel efficiency, and poor engine performance.
Possible causes	– Faulty or failing O2 sensor – Exhaust leaks near the O2 sensor – Contaminated or dirty O2 sensor – Issues with the vehicle’s fuel system or injectors – Shorted or open wiring in O2 sensor circuit – Faulty Powertrain Control Module (PCM)
How to diagnose?	Scan for Codes: Always start by scanning the vehicle for codes. This will give an indication of where the problem might be. Inspect the O2 Sensor: Check the O2 sensor for any visible damage or contamination. Check for Exhaust Leaks: Inspect the exhaust system, especially near the O2 sensor, for any leaks. Test the O2 Sensor: Using a digital multimeter or a scan tool, monitor the O2 sensor’s voltage. It should fluctuate between 0.1 and 0.9 volts. Inspect Wiring and Connectors: Check the wiring and connectors leading to the O2 sensor. Look for any signs of damage, corrosion, or disconnection. Check Fuel System: Inspect the fuel system for any issues that might cause a rich or lean condition. PCM Inspection: In rare cases, a faulty PCM might be the cause. Ensure the PCM is functioning correctly.

How to fix P014C – learn from mechanics

I looked into P014C service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: RAM

Vehicle Information 2012 Ram 3500 SLT 6.7L

Issue + Repair History

• MIL light on with codes P014C and P014D.
• Vehicle was previously serviced 6 weeks ago for the same codes.
• Wiring harness overlay was performed as per TSB 25-002-14.
• B1S1 was replaced.
• EGR valve observed to have a slight leak.
• MAF is functioning correctly, and there are no misfires or intake leaks.

Other OBD2 Codes + Test Results

• P014c: B1S1 slow lean to rich
• P014d: B1S1 slow rich to lean

What Are People Suggesting to Fix the Issue

• Perform an injector balance test.
• Monitor O2 sensors readings and ensure they don’t vary more than 4% from each other.
• Check PCM for the latest software and update if necessary.
• Fix the leaking EGR valve.

What Was the Final Fix Replaced the EGR valve.

Case #2: Nissan

Vehicle Information 2016 Nissan Altima S 2.5L

Issue + Repair History

• MIL light on.
• Vehicle is a fleet vehicle, mostly driven on highways and well-maintained.
• Other Nissan Altimas in the fleet haven’t shown these issues.
• All four current recalls have been addressed.
• PCM updated twice.
• PCV had the updated unit installed.
• Front A/F sensor was replaced under warranty.
• MAF cleaned and replaced.
• Fuel pressure checked.
• Front and rear O2 sensors replaced.
• PCM reflashed at a Nissan dealer.

Other OBD2 Codes + Test Results

• P015b: O2 Sensor Delayed response- Lean to Rich Bank 1 Sensor 1
• P015a: O2 Sensor Delayed response- Rich to Lean Bank 1 Sensor 1
• P014d: O2 Sensor Slow response- Lean To Rich Bank 1 Sensor 1
• P014c: O2 Sensor Slow response- Rich To Lean bank 1 Sensor 1

What Are People Suggesting to Fix the Issue

• Refer to TSB NTB16-117b which calls for various replacements and modifications.
• Return to the dealer for warranty work.
• Check for a PCC valve or vacuum leak causing slow response.
• A/F sensor failures might be due to increased under-hood temperatures caused by cutting the front plastic lower cover.

What Was the Final Fix

• PCV replaced.
• A/F sensor replaced twice.
• Software updated.
• Planning to visit a different dealer with the mentioned TSB for further solutions.

Case #3: Ram

Vehicle Information 2012 Ram 2500 SLT 6.7L

Issue + Repair History

• Excessive black smoke from exhaust.
• Loss of power.
• EGR and turbo cleaned due to excessive dirt.
• Turbo turns but no pressure.
• Recent fuel filter replacement and regular oil changes.

Other OBD2 Codes + Test Results

• P2706: MS Solenoid Circuit
• P242f: DPF Restriction
• P2463: DPF Soot
• P013a/p014c: Slow O2 response
• P003a: Turbo Exceeding limit
• 049d: EGR Exceeding Limit

What Are People Suggesting to Fix the Issue

• Consider the driving cycle; vehicles not driven long enough on the road might generate more soot in the Aftertreatment System.
• Check for any Charge Air Cooler or other air induction system leaks.
• Try performing a DPF regen in the shop with a scan tool.
• The DPF and exhaust might be restricted, leading to a no-boost, low power situation.
• Check the MAP readings and see if the catalyst is clogged.
• The variable turbo actuator might be seized or stuck.
• DPF pressure sensors could be plugged.
• Consider issues upstream, like a bad injector, EGR, or variable actuator.
• Restricted exhaust should be addressed first; removing any Ox sensor before any cat or muffler might help diagnose the issue.

What Was the Final Fix

• Replaced Turbocharger.
• Crankcase filter on top of valve cover replaced.
• EGR and emission sensors cleaned.
• Used Bardahal EGR Cleaner to clean up residual soot in the exhaust.
• Power was restored after addressing the sticky wastegate on the turbo

Advice	Brief Description of Diagnostic Step
Check O2 Sensors	Monitor the O2 sensor readings, especially the switching and voltage. If irregularities are found, consider replacing the sensor.
Inspect for Exhaust Leaks	Check for any leaks in the exhaust system, especially near the O2 sensors, as they can affect sensor readings.
Consider Vehicle’s Driving Cycle	Vehicles not driven long enough on the road might generate more soot in the Aftertreatment System, affecting sensor readings.
Perform DPF Regen	Use a scan tool to perform a Diesel Particulate Filter regeneration to clear out soot and restore filter function.
Check for Air Induction Leaks	Inspect the Charge Air Cooler and other air induction systems for any leaks that might affect the exhaust system.
Update or Reflash PCM	Ensure the Powertrain Control Module has the latest software. If not, consider updating or reflashing it.
Clean EGR and Turbo	Excessive dirt or soot in the EGR and turbo can affect performance. Cleaning them can restore proper function.