How much does it cost to replace the O2 sensor on a Subaru Forester?

Most Forester owners can expect to pay roughly $200–$500 per O2 sensor replacement, including parts and labor. Prices vary by sensor type (upstream vs downstream), whether you use OEM or aftermarket parts, the model year, and regional labor rates.

In this article, we break down the factors that influence pricing, outline typical ranges, and offer practical tips to help you estimate and potentially reduce the cost when servicing your Forester’s oxygen sensors.

What determines the cost

Costs hinge on the type of sensor, the parts you choose, how many sensors need replacement, and where you go for service. The Forester’s exhaust setup often includes multiple O2 sensors, which can raise the total bill if more than one needs replacement.

Below is a snapshot of the main cost components you’re likely to encounter when replacing an O2 sensor on a Forester.

• Parts cost: OEM Subaru sensors generally cost more than aftermarket alternatives. Typical ranges are:
  
  
  
  • Aftermarket (non-OEM) sensors: about $40–$120 per sensor
  
  
  • OEM/Subaru sensors: about $90–$250 per sensor
  
  
  • Some high-quality brands can run higher, up to about $300 per sensor
  
  
  
  


• Labor cost: Labor rates vary by region and shop, with typical times to replace a single O2 sensor around 0.5–1.5 hours. In many markets, labor costs roughly align with:
  
  
  
  • Independent shop: about $60–$150 per hour
  
  
  • Dealership or specialty shop: about $100–$180 per hour
  
  
  
  


• Number of sensors: Foresters commonly have 1–4 O2 sensors depending on engine and year. Replacing more than one sensor increases the total cost proportionally.


• Diagnostic and ancillary fees: Some shops charge a diagnostic fee if no repair is performed, or waive it if the repair is completed at their shop. This can add $0–$100 to the bill.

In short, the total cost is the sum of parts and labor, multiplied by the number of sensors replaced, and influenced by where you have the work done and which parts you select.

Estimated price ranges by scenario

The ranges below reflect typical U.S. pricing and include both parts and labor. They assume a standard replacement of a single O2 sensor or a straightforward job for two sensors; dealer pricing tends to be higher, while independent shops often offer lower rates. Prices can vary by model year and engine configuration.

• Single sensor replacement (aftermarket parts): Parts $40–$120; Labor $60–$120; Estimated total $100–$240


• Single sensor replacement (OEM/Subaru parts): Parts $90–$250; Labor $60–$120; Estimated total $150–$370


• Two sensors replaced (both aftermarket parts): Parts $80–$240; Labor $120–$240; Estimated total $200–$480


• Two sensors replaced (both OEM/Subaru parts): Parts $180–$500; Labor $120–$240; Estimated total $300–$740

Note: If your Forester requires four O2 sensors, multiply these ranges accordingly and be prepared for higher totals, especially with OEM parts or dealer service.

Ways to save on O2 sensor replacement

Smarter shopping and small trade-offs can cut costs without compromising reliability. Consider these strategies.

• Shop around for quotes from independent repair shops as well as dealerships to compare labor rates and part prices.


• Ask for a written price that breaks out parts and labor, and confirm whether diagnostic fees are included or waived if you proceed with the repair.


• Consider aftermarket sensors if you’re comfortable with non-OEM parts; they are often significantly cheaper and can be reliable for many drivers.


• Ask the shop to replace only the sensor(s) that are failing or triggering codes, rather than the entire exhaust sensor system, to keep costs lower.


• Check for potential underlying causes (e.g., exhaust leaks or wiring issues) that might cause a sensor failure to recur; addressing these upfront can prevent repeated visits.

Always obtain a written estimate before work begins and verify what is included in the final price to avoid surprise charges.

Summary

The cost to replace an O2 sensor on a Subaru Forester depends on sensor type, number of sensors, parts choice (OEM vs aftermarket), and labor rates. Expect roughly $100–$240 for a single aftermarket sensor, $150–$370 for a single OEM sensor, and proportionally higher totals for two sensors or more. Prices vary by model year, region, and shop, with independent garages typically offering more competitive rates than dealers. Shopping around, opting for appropriate parts, and confirming pricing in advance can help you manage the total cost.

How many O2 sensors does a Subaru Forester have?

A Subaru Forester typically has two oxygen sensors, one located before the catalytic converter and one after. Some models may have more, with the total number varying based on the year, trim, and engine. Your vehicle's service manual will provide the most accurate information for your specific model.
 

• One before the catalytic converter: This is often called the Air/Fuel Ratio (AFR) sensor and is upstream.
• One after the catalytic converter: This is typically referred to as the Oxygen (O2) sensor and is downstream.

To determine the exact number for your vehicle, consult your owner's manual or a professional mechanic, as some configurations have additional sensors.

How much would a mechanic charge to replace an O2 sensor?

The total cost to replace an O2 sensor typically ranges from $200 to $500 for parts and labor, though some sources suggest a slightly lower average of $200 to $350 for standard vehicles. The final price depends on factors like vehicle make and model, labor costs, parts cost, and whether the sensor is in an accessible or hard-to-reach location. DIY replacement is an option, with parts costing anywhere from $20 to $300 or more.
 
Cost breakdown

• Parts: The cost for a new oxygen sensor can range from $20 to over $300, depending on the brand, vehicle, and type of sensor. 
• Labor: Professional installation typically costs between $150 and $600, depending on the complexity and hourly labor rates at your shop. Some jobs, especially if the sensor is hard to access or rusted in place, can be more expensive. 
• DIY: If you are comfortable doing the work yourself, you can save on labor costs. Parts can range from $20 to $300 or more, making the total cost for a DIY replacement between $20 and $300. 

Factors that affect the cost

• Vehicle: Luxury vehicles may have higher parts and labor costs than standard passenger cars. 
• Location: Labor rates vary by geographic location. 
• Sensor type: Upstream sensors (before the catalytic converter) can be slightly more expensive than downstream sensors (after the converter). 
• Accessibility: A sensor that is difficult to reach due to its location will likely require more labor time and therefore increase the total cost. 

Signs that you may need an O2 sensor replacement
Your check engine light is on, Decreased fuel economy, Rough engine idle or misfires, A smell of rotten eggs from the exhaust, and Engine hesitation.

Can I still drive with a bad O2 sensor?

You can still drive with a bad O2 sensor, but it is not recommended because it can lead to poor fuel economy, engine misfires, and damage to the catalytic converter. Driving with a faulty sensor is generally safe for short distances, but it is best to get it replaced as soon as possible to avoid more expensive repairs. 
This video explains the potential consequences of driving with a bad O2 sensor: 42sMy Auto LifeYouTube · Sep 6, 2024
Risks of driving with a bad O2 sensor

• Poor fuel economy: The engine may run too rich (using too much fuel) or too lean (using too little fuel), which lowers your gas mileage. 
• Engine damage: Running the engine with the wrong air-fuel mixture can lead to poor performance, misfires, and potentially harm other components. 
• Catalytic converter damage: A consistently rich fuel mixture can cause unburnt fuel to enter the catalytic converter, overheating and clogging it, which is an expensive part to replace. 
• Failed emissions tests: A bad O2 sensor will likely cause your vehicle to fail an emissions test due to higher pollution levels. 

What to do

• Schedule a replacement: Since the issue can lead to costly damage, it is best to have the O2 sensor replaced by a mechanic as soon as you can. 
• Monitor performance: Pay attention to changes in your car's performance, such as rough idling, poor acceleration, or a check engine light, and address them promptly. 

Is it worth fixing an O2 sensor?

A: Yes, replacing a faulty oxygen sensor can improve fuel efficiency by ensuring proper air-fuel mixture and combustion.