Fix P015B: Mechanic’s solutions that WORKED

The code P015B: O2 Sensor Delayed Response – Lean to Rich Bank 1 Sensor 1 points out a fault in the oxygen sensor’s response time, and most likely is caused by exhaust leaks or malfunctioning O2 sensors.

P015B quick overview

Meaning	P015B: O2 Sensor Delayed Response – Lean to Rich Bank 1 Sensor 1
Is it serious?	Yes, it can affect fuel efficiency, emissions, and overall engine performance.
Possible causes	– Exhaust leaks near the O2 sensor – Faulty or “lazy” O2 sensor – Fuel contamination – Malfunctioning PCV valve – Vacuum leaks in the intake system – Stuck open purge solenoid – Software issues in the Powertrain Control Module (PCM/ECM)
How to diagnose?	Visual Inspection: Check the exhaust system for any visible cracks, leaks, or damage. Test the O2 Sensor: Use a scanner to monitor the O2 sensor’s operation to ensure it’s responding correctly. Check for Software Updates: Ensure the PCM/ECM has the latest software updates. Fuel Sample Test: Pull a fuel sample to check for contamination. Inspect the PCV Valve: Ensure the PCV valve is functioning correctly. Smoke Test: Conduct a smoke test to check for vacuum leaks in the intake system. Check the Purge Solenoid: Ensure the purge solenoid isn’t stuck open. Consult Technical Service Bulletins (TSBs): Check for any TSBs related to the P015B code for the specific vehicle make and model.

How to fix P015B – learn from mechanics

I looked into P015B 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: Chevrolet

Vehicle Information 2013 Chevrolet Avalanche Black Diamond LTZ 5.3L

Issue + Repair History MIL lamp on. Previously replaced Oxygen sensor OE bank 1 sensor 1, but the same fault returned after a drive cycle.

Other OBD2 Codes + Test Results P015b- Delayed Response Lean To Reach Bank-1 Sensor-1.

What are people suggesting to fix the issue

• Check air filter & clean MAF. Consider the possibility of E85 gas and look at monitored stats in mode 06.
• Examine fuel trims for more information.
• Inspect the catalytic converter on the affected bank.
• Smoke test the exhaust system for potential cracks or leaks near the O2 sensor.
• Consider an ECM reflash and check for any updates related to the issue.

What was the final fix Replaced both front OE 12583804 Oxygen Sensor and installed a new 22846471 Negative Battery Cable due to rust on chassis ground from being an east coast car.

Case #2: Chevrolet

Vehicle Information 2016 Chevrolet Cruze LT 1.4L

Issue + Repair History Car initially ran poorly with only code p0137 in the PCM. After replacing b1s2, the car ran better. However, six days later, the car started running poorly again. It starts, runs okay for a minute, then the idle becomes rough, begins to misfire, throttle does not respond to the accelerator pedal position, and eventually stalls. After warming up, it runs slightly better but still not optimally. It shows a rich condition with a long-term fuel trim of -28. Previously, b1s2 was replaced and was functioning correctly.

Other OBD2 Codes + Test Results
p0137- b1s2 low voltage Observed b1s2 – not changing, skewed.

P015B

What are people suggesting to fix the issue

• Smoke test the exhaust system to check for leaks.
• Check the signal wire for a short to ground.
• Pull a fuel sample from the tank to check for contamination.
• Check ECT and IAT before cold startup.
• Check for fuel-laden oil and over-thinned oil.
• Examine potential airflow issues like a MAF reading being off or a clogged CAT.
• Disconnect BOTH O2s to force open loop and monitor data.
• Check the main harness plug for the injectors and coils for water/antifreeze intrusion.
• Ensure the use of an OEM sensor.
• Look at ECT, IAT, MAF, and fuel rail pressure. Consider the possibility of leaking injectors.
• Check throttle body air compensation.
• Consider exhaust leaks as a primary cause for the P015B code and the use of non-OEM sensors.

What was the final fix Both oxygen sensors were replaced simultaneously, and the car’s operation returned to normal. However, after a few days, the engine light came on with a p015b code. After extensive checking and observing soot-like deposits on the oxygen sensors, the car was sent to the dealer for a program update.

Case #3: Nissan

Vehicle Information 2016 Nissan Altima S 2.5L

Issue + Repair History This fleet vehicle, primarily driven on highways and well-maintained, displayed issues not seen in other Nissan Altimas of the fleet. All current recalls have been addressed. The vehicle’s PCM has been updated twice, and an updated PCV unit was installed. The first dealer claimed the car had the incorrect PCV. The front A/F sensor was replaced under warranty during this service. Previously, the MAF was cleaned and replaced, fuel pressure was checked, and both the front and rear O2 sensors were replaced. The PCM was also 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 multiple replacements and modifications including the PCV valve, ECM reprogramming, grille shutter modifications, and more.
• The issue might be related to previous warranty work, suggesting a return to the dealer.
• Potential causes could be a PCC valve or a vacuum leak causing the slow response.

What was the final fix Both oxygen sensors were replaced, and the dealer updated the software. The vehicle was then taken to a different dealer with the mentioned TSB for further actions. Another vehicle in the fleet exhibited the same issue.

Case #4: Chevrolet

Vehicle Information 2013 Chevrolet Silverado 1500 LT 5.3L

Issue + Repair History This 2013 Silverado has an intermittent misfire on Cylinder #3, a non-AFM shutting down cylinder. Misfire history also shows occasional misfires on Cylinders #5 and #7. The spark plug, coil, plug wire, and injector have been swapped with other cylinders, but the issue persists. Compression and leakdown tests are satisfactory. Valve/cam lift measurements for Cylinder #3 are similar to Cylinder #1, which doesn’t show any misfires. Manifold vacuum at idle is steady at 18″. The front O2 sensors were swapped to the other bank. The vehicle only shows misfires at idle, not while driving. The EVAP and O2 codes have been reset by the customer in the past. The EVAP system was smoke tested and found to have no leaks. The intake was also smoke tested, and the MAF sensor was cleaned. The vehicle’s PCM has been updated twice, and the PCV has had the updated unit installed. The front A/F sensor was replaced under warranty.

Other OBD2 Codes + Test Results

• p0303- Cyl #3 Misfire
• p015b- HO2S Delayed Lean to Rich Response B1S1
• p455 – EVAP Large Leak
• Compression Test – Cyl #1 205 psi, Cyl #3 200 psi
• Running Compression Test – Cyl #1 105-110 psi, Cyl #3 80-90psi
• Fuel pressure – 46 psi idle, 75 psi KOEO FP relay energized
• Valve/Cam Lift at Rocker arm oil hole – Cyl #1 Intake .236

What are people suggesting to fix the issue

• Perform a crank relearn.
• Check for grounding on bank 1 at the rear of the cylinder head.
• Check for a purge solenoid leak causing misfire and EVAP leak.
• The difference in running compression indicates a mechanical issue, possibly with the valve train.
• Check for worn roller on lifter and camshaft surface.
• Check for sticking valves, weak valve spring, or intermittent lifter collapse.
• Check the purge valve to ensure it isn’t stuck open.
• Remove the valve cover and loosen the rocker arms on the misfiring cylinder while idling to see if the misfire resolves.
• Check for a weak valve spring.
• Use freeze frame data to check for good vacuum reading. After a freeway test drive, use an emission gas analyzer to check for hydrocarbon readings in the coolant bottle.
• Perform a carbon and fuel injector cleaning.
• Turn valve springs by hand to check for breaks.

What was the final fix The cam and lifters were suspected to be worn. The #3 exhaust pushrod and rocker arm were found to be worn where they meet. Misfires diminished but were still occasionally present. The technician believes there was a valve train problem, but the customer decided to trade the truck before further investigation.

Advice	Brief Description of Diagnostic Step
Check for exhaust leaks	Inspect the exhaust system for any cracks, leaks, or damage.
Replace Oxygen (O2) Sensors	Consider replacing the front and/or rear O2 sensors if they are faulty.
Check for proper sensor operation	Ensure that the O2 sensors are functioning correctly and not “lazy”.
Reprogram or update the PCM/ECM	Check for software updates for the Powertrain Control Module (PCM/ECM).
Inspect for fuel contamination	Pull a fuel sample and ensure there’s no contamination.
Check the PCV valve	Ensure the Positive Crankcase Ventilation (PCV) valve is functioning and not causing issues.
Inspect for vacuum leaks	Use smoke tests or other methods to check for leaks in the intake system.
Check the purge solenoid	Ensure the purge solenoid isn’t stuck open, which could cause misfires.