If you're seeing the dreaded Check Engine Light (CEL) on your dashboard and your Honda Civic 1.8L is throwing the P0134 or P0135 error codes, you're not alone.
These are the most common fault codes for the 8th Gen Civic (2006-2011), typically indicating a dead Upstream Oxygen Sensor.
In this guide, we will break down the issue and show you how to fix it yourself for a fraction of the dealer's price.
(Note: P0134 is a specific code. If you are experiencing other issues like poor gas mileage without a code, read our broader guide on [👉 Common Symptoms of a Bad O2 Sensor] to verify the problem first.)
The Diagnosis: What Does P0134 & P0135 Mean?
Both codes point to a failure in the Air Fuel Ratio Sensor (Sensor 1), which is located before the catalytic converter.
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P0134 (No Activity): The sensor is "dead" or reading incorrectly. The ECU isn't receiving a signal, often due to sensor degradation.
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P0135 (Heater Circuit Malfunction): The internal heating element inside the sensor has failed. The sensor can't reach operating temperature quickly enough to work.
Wait, is this the Upstream or Downstream sensor?
These codes specifically refer to the Upstream sensor (Sensor 1). It is critical not to buy the wrong one.
(Not sure about the difference? Read our guide: [👉 Upstream vs. Downstream O2 Sensors Explained])
Why Can’t I Just Clean My Old Sensors?
You might be tempted to clean your sensors to save money. However, for codes like P0135 (Heater Failure), cleaning is useless.
The heating element is an internal electrical component. Once the circuit is broken inside the metal shell, no amount of cleaning will fix it. The only reliable solution is to replace it with an OEM-standard part.
Cost Analysis: Mechanic vs. DIY
Before you head to the repair shop, let’s look at the math.
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Mechanic Price: According to RepairPal, replacing a single Air Fuel Ratio sensor on a Civic can range from $250 to $450. Dealers often mark up the part price significantly.
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DIY Price: If you do it yourself, you only pay for the part. Automotive Leader offers OEM-quality replacements (Part Number: 36531-RNA-A01) for a fraction of that cost.
Your Estimated Savings: $200+
[👉 Check Price for Honda Civic 1.8L Upstream O2 Sensor (36531-RNA-A01)]
The Solution: Direct Fit Replacement
The easiest way to solve your Honda Civic's P0134 or P0135 code is by replacing the faulty unit. We recommend our Automotive Leader sensor set, which is specifically calibrated for the Honda Civic 1.8L engine (R18A1).
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OEM Quality: Meets specific resistance standards for the Honda ECU.
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Direct Fit: Correct plug shape and wire length. No cutting or splicing required.
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Fast Shipping: Ships from our US warehouse.
[👉 Shop Honda Civic 1.8L Oxygen Sensor Set (Upstream & Downstream)]
Installation Guide: 5 Steps to Fix It
Installing the new upstream O2 sensor on your Honda Civic is a straightforward job that can be done in under an hour.
Tools You’ll Need:
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22mm Oxygen Sensor Socket (or a 7/8" wrench)
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Ratchet
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Penetrating oil (like WD-40) if the sensor is rusted
Step-by-Step:
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Locate the Sensor: Pop the hood. The Upstream sensor is screwed directly into the exhaust manifold (right in front of the engine block).
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Disconnect: Unclip the electrical connector.
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Remove: Use your 22mm socket to unscrew the old sensor. (Tip: Do this when the engine is slightly warm, but not hot).
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Install: Screw in the new [Automotive Leader O2 Sensor] by hand, then tighten with the wrench.
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Clear Codes: Reconnect the battery or use an OBD-II scanner to clear the P0134/P0135 codes.
FAQ: Common Questions
Q: Do I need to replace both sensors?
A: If your car has high mileage (over 100k miles), it is highly recommended to replace both the Upstream (Air Fuel Ratio) and Downstream sensors together to restore peak fuel economy.
(View our [👉 2-Piece Set for Honda Civic] for a bundle discount.)
Q: Will this fix my "Check Emission System" light?
A: Yes, on the Honda Civic, the P0134/P0135 codes often trigger a "Check Emission System" warning on the dash. Replacing the sensor usually clears this.
Conclusion: Fix It Now
Don’t let a $50 part cause long-term damage to your catalytic converter. Replacing the upstream sensor on your Honda Civic 1.8L is simple.
Ready to get your Civic running smoothly again?
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