🔧 Accord - Oxygen Sensor Replacement

Your Accord has two exhaust sensors: an upstream Air/Fuel (A/F) sensor (Sensor 1) and a downstream O2 sensor (Sensor 2). Replacing the correct one matters because they sit in different locations and fix different trouble codes.

Difficulty Level: Intermediate | Estimated Time: 0.5-1.5 hours

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⚠️ Safety & Precautions

• ⚠️ Exhaust parts get extremely hot—work on a fully cool engine.
• ⚠️ If lifting the car, support it with jack stands on solid, level ground—never rely on a jack alone.
• ⚠️ Avoid pulling on the sensor wires; only handle the connector and the sensor hex.
• 🔌 Battery disconnect is not required, but it’s OK to disconnect the negative terminal if you’re worried about shorting a connector.

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🔧 Required Tools

You'll need the following tools for this repair:

• Safety glasses
• Nitrile gloves
• Floor jack (rated 2-ton minimum)
• Jack stands (rated 2-ton minimum)
• Wheel chocks
• Work light
• 22mm oxygen sensor socket (7/8")
• 3/8" drive ratchet
• 3/8" drive breaker bar
• 3/8" drive extension set
• Torque wrench (10-100 Nm range)
• 10mm socket
• Phillips screwdriver
• Trim clip removal tool
• OBD2 scan tool (basic code reader)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Upstream A/F sensor (Sensor 1) - Qty: 1
• Downstream O2 sensor (Sensor 2) - Qty: 1
• Anti-seize compound - Qty: 1
• Penetrating oil - Qty: 1
• Replacement splash shield clips - Qty: 1 set

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📋 Before You Begin

• 🧭 Identify which sensor you need:
  • Sensor 1 (Upstream A/F): threaded into the exhaust manifold at the front of the engine bay.
  • Sensor 2 (Downstream O2): threaded into the exhaust pipe after the catalytic converter, accessed from underneath.
• 🧰 If you have a check engine light, plug in your OBD2 scan tool and write down the codes first.
• 🚗 Park on level ground. Set the parking brake. Place wheel chocks behind the rear wheels.
• 🧊 Spray penetrating oil on the sensor threads (where it meets the pipe/manifold) and wait 10–15 minutes.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Confirm which sensor you’re replacing

• Use the OBD2 scan tool to read codes.
• If you tell me the code(s) (example: P0138, P0420), I can confirm which sensor is most likely the correct one.

Step 2A: Replace Sensor 1 (Upstream A/F sensor) from the top

• Open the hood and locate the sensor on the exhaust manifold (front side of the engine).
• Unclip any harness retainers using the trim clip removal tool.
• Disconnect the sensor electrical connector by hand (press the lock tab, then pull apart).
• Install the 22mm oxygen sensor socket (7/8") over the sensor and loosen it using a 3/8" drive breaker bar.
• Remove the sensor the rest of the way with the 3/8" drive ratchet.
• If the new sensor threads are not pre-coated, apply a tiny amount of anti-seize compound to the threads only. Keep it off the tip.
• Thread the new sensor in by hand first to avoid cross-threading.
• Tighten with the torque wrench and 22mm oxygen sensor socket (7/8"): Torque to 44 Nm (33 ft-lbs).
• Reconnect the connector and re-secure the harness with the trim clip removal tool as needed.

Step 2B: Replace Sensor 2 (Downstream O2 sensor) from underneath

• Lift the front of the car using the floor jack (rated 2-ton minimum) and support it on jack stands (rated 2-ton minimum).
• Remove the lower splash shield if it blocks access:
  • Remove bolts with a 10mm socket.
  • Remove clips with a trim clip removal tool and/or Phillips screwdriver.
• Locate the downstream sensor on the exhaust pipe after the catalytic converter.
• Unclip harness retainers with the trim clip removal tool, then disconnect the electrical connector by hand.
• Loosen the sensor using the 22mm oxygen sensor socket (7/8") and a 3/8" drive breaker bar.
• Remove the sensor with the 3/8" drive ratchet and extension as needed.
• If needed, apply a small amount of anti-seize compound to the new sensor’s threads only. Do not contaminate the tip.
• Install the new sensor hand-tight first, then torque it with the torque wrench: Torque to 40 Nm (29 ft-lbs).
• Reconnect the connector, re-clip the harness, reinstall the splash shield using the 10mm socket and clips.
• Lower the car safely using the floor jack (rated 2-ton minimum).

Step 3: Clear codes and verify the fix

• Use the OBD2 scan tool to clear stored codes.
• Start the engine and listen for exhaust leaks (a sharp “ticking” near the sensor area can mean it’s loose).
• Test drive 10–15 minutes, then re-scan with the OBD2 scan tool to confirm no codes returned.

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✅ After Repair

• 🔍 Re-check the sensor connector is fully latched and the harness is not touching the exhaust.
• 🛑 If a code returns immediately, stop and re-check for cross-threading, a damaged connector pin, or a blown fuse feeding the heater circuit.
• 🚗 If you were chasing a catalyst efficiency code (like P0420), a new downstream sensor may not fix it—tell me the code and I’ll guide you.

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💰 DIY vs Shop Cost

Shop Cost: ₹6,000-₹18,000 (parts + labor)

DIY Cost: ₹3,500-₹12,000 (parts only)

You Save: ₹2,500-₹6,000 by doing it yourself!

Shop labor rates vary in Panipat, but this job is typically ~0.5-1.5 hours.

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🎯 Ready to get started?

HowToo makes it easy: same-day/2-day shipping on every part, plus all the tools and specialty tools you need! Check out the parts and tools sections below to add everything to your cart.

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Quick question (so I point you to the correct sensor):

• Which one are you replacing: upstream (Sensor 1) or downstream (Sensor 2)?
• What OBD2 code(s) are you getting (if any)?