P0159
Fix within 1-2 weeksYour engine's computer detected that the downstream oxygen sensor on Bank 2 (the side of the engine without cylinder #1) is reacting too slowly to changes in exhaust gas. This sensor monitors the efficiency of your catalytic converter.
Code P0159 means your Bank 2 Sensor 2 O2 sensor is responding slowly. Common causes: Faulty O2 sensor (80%), exhaust leak (15%). Drivability: Yes, safe to drive. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0159?
Yes, safe to drive
No restrictions
Stop driving immediately if: Flashing CEL, loud noises from the exhaust, or a strong rotten egg smell.
Symptoms of P0159
- 1Check Engine Light is on
- 2Reduced fuel economy (sometimes)
- 3Failed emissions test
Common Causes of P0159
Parts most likely causing this code, ranked by probability
The oxygen sensor itself is worn out or contaminated and can no longer respond quickly enough to changes in exhaust oxygen levels.
80% of P0159 cases are fixed by replacing this part
An exhaust leak near the sensor can draw in outside air, causing the sensor to read incorrectly or respond slowly.
15% of P0159 cases are fixed by repairing an exhaust leak
Damaged wires or corroded connections to the oxygen sensor can prevent it from sending accurate or timely signals to the engine computer.
5% of P0159 cases are fixed by repairing wiring or connectors
Check These First (Before Buying Parts)
- Visually inspect the Bank 2 Sensor 2 oxygen sensor and its wiring for any obvious damage, fraying, or corrosion.
- Listen and look for exhaust leaks near the sensor. Use soapy water on cold exhaust pipes to find bubbles if you suspect a leak.
How to Diagnose P0159
- 1Visually inspect the Bank 2 Sensor 2 oxygen sensor and its wiring for any damage, fraying, or corrosion.
- 2Check for any exhaust leaks near the Bank 2 Sensor 2 oxygen sensor. Listen for hissing sounds or look for soot marks.
- 3Use an OBD-II scan tool to monitor the live data stream of the Bank 2 Sensor 2 oxygen sensor. Observe its voltage fluctuations and response time.
- 4If the sensor appears faulty, test its heater circuit resistance and signal output with a multimeter.
P0159 on Popular Vehicles
Toyota Camry
2007-2024P0159 on Toyota Camry models is frequently resolved by replacing the downstream O2 sensor. These sensors are common wear items around 100,000-150,000 miles.
85% fixed by replacing the O2 sensor
Honda Accord
2003-2024Honda Accord vehicles often experience P0159 due to a failing Bank 2 Sensor 2. Exhaust leaks, particularly at flex pipes or manifold gaskets, can also trigger this code.
80% fixed by replacing the O2 sensor
Ford F-150
2004-2024For Ford F-150 trucks, P0159 is a common code. The Bank 2 Sensor 2 O2 sensor is a frequent failure point. Due to the truck's exhaust routing, exhaust leaks are also a significant cause.
75% fixed by replacing the O2 sensor
Frequently Asked Questions
What does P0159 mean?
P0159 indicates that the downstream oxygen sensor on Bank 2 (the side of the engine without cylinder #1) is showing a slow response time. This sensor monitors your catalytic converter's efficiency.
Can I drive with P0159?
Yes, you can drive safely with P0159. The code indicates a slow sensor response, not an immediate engine failure. However, you should fix it within 1-2 weeks to prevent potential long-term issues.
Will P0159 clear itself?
No, P0159 will not clear itself. The engine computer detects a persistent slow response from the oxygen sensor. You need to diagnose and fix the underlying issue, then clear the code with a scan tool or by completing several drive cycles after the repair.
How do I fix P0159 myself?
Start by inspecting the Bank 2 Sensor 2 oxygen sensor and its wiring for damage. Check for exhaust leaks near the sensor. If no issues are found, replacing the Bank 2 Sensor 2 oxygen sensor is the most common fix. You'll need an O2 sensor socket and a wrench.
How much does it cost to fix P0159?
The cost to fix P0159 yourself is typically $50-$150 for a new oxygen sensor. If you take it to a shop, expect to pay $150-$500, which includes parts and 1-2 hours of labor.
P0159 keeps coming back - why?
If P0159 keeps returning, it often means the initial diagnosis was incomplete. Double-check for subtle exhaust leaks, thoroughly inspect the wiring and connector for corrosion or damage, or consider if the new sensor itself is faulty. In rare cases, a failing catalytic converter or engine computer could be the cause.
Will P0159 fail emissions/smog test?
Yes, P0159 will cause your vehicle to fail an emissions or smog test. A Check Engine Light due to this code indicates an issue with the emissions monitoring system, which is a direct failure point for inspections.
What's the difference between P0159 and P0430?
P0159 means the Bank 2 Sensor 2 oxygen sensor itself is responding slowly. P0430 means the catalytic converter on Bank 2 is not working efficiently enough. While related, P0159 points to a sensor issue, and P0430 points to a converter issue, though a slow sensor can sometimes be a symptom of a failing converter.
P0159 on Ford F-150?
On Ford F-150s, P0159 is commonly caused by a failing Bank 2 Sensor 2 oxygen sensor, especially on models with higher mileage. Exhaust leaks are also a common culprit on these trucks due to their exhaust system design. Always check for leaks first.
Questions to Ask Your Mechanic
Did you check for exhaust leaks near the Bank 2 Sensor 2 O2 sensor?
Good answer: Yes, I performed a smoke test and visual inspection and found no leaks. The exhaust system is sealed.
What were the live data readings for the Bank 2 Sensor 2 O2 sensor's voltage and response time?
Good answer: The sensor's voltage was fluctuating slowly, taking over 500 milliseconds to switch, which is outside the normal operating range for a healthy sensor.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-2 hours
Intermediate - requires specific tools like an O2 sensor socket and potentially a scan tool for diagnosis, along with safely lifting the vehicle.
Cost of Waiting
Ignoring P0159 can lead to reduced fuel economy and, more importantly, can cause premature failure of your catalytic converter. A $50-$150 oxygen sensor replacement now prevents a $800-$2,500 catalytic converter replacement later.
While You're In There...
If you find an exhaust leak, you'll need to replace the gasket at the leak point. It's also good practice to replace any gaskets disturbed during O2 sensor removal.
Applying anti-seize to the threads of the new O2 sensor prevents it from seizing in the exhaust pipe, making future removal much easier.
Tools You'll Need
- OBD-II Scan Tool
- Oxygen Sensor Socket
- Ratchet and Extensions
- Jack and Jack Stands (or vehicle lift)
- Safety Glasses
- Gloves
- Wire Brush (for exhaust threads)
P0159 is a common emissions code. Most repairs involve replacing a worn-out oxygen sensor, which is a straightforward fix that will get your vehicle running efficiently again.
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Your Next Steps
Step 1: Visually inspect the Bank 2 Sensor 2 oxygen sensor and its wiring for any physical damage or corrosion. Check for exhaust leaks around the sensor.
Step 2: If no obvious issues are found, use an OBD-II scan tool to monitor the live data for the Bank 2 Sensor 2 O2 sensor. Look for slow voltage changes compared to other O2 sensors.
Step 3: If the sensor's response is confirmed slow, the most likely fix is replacing the Bank 2 Sensor 2 oxygen sensor. You'll need an O2 sensor socket for this job.