P0138 on 2011-2016 Honda CR-V: Downstream O2 Sensor High Voltage Causes and Fixes

What's Unique About the 2011-2016 Honda CR-V

The Honda CR-V's 2.4L K-series engine is known for its reliability, but oxygen sensors are a common wear-and-tear item. For this vehicle range, the most important factor is the generational split. The 2011 model is the last of the 3rd generation, while 2012-2016 models are the 4th generation, which received engine updates. This means you must verify the correct O2 sensor part number for your specific year and engine code (K24Z6, K24Z7, or K24W9) to ensure compatibility. Using a generic or incorrect part can lead to the code returning.

Generation note: This range covers two CR-V generations. The 2011 model is the final year of the third generation (RE), while 2012-2016 models belong to the fourth generation (RM). They use different evolutions of the 2.4L K-series engine, so the downstream O2 sensor part number is different. Always verify the part with your vehicle's VIN or specific engine code. For example, the OEM part for a 2011 CR-V is 36532-REZ-A01, while the 2012-2014 model uses 36532-R5A-A01, and the 2015-2016 model uses 36532-5LA-A01.

Symptoms You May Notice

• Check Engine Light is on
• Failure to pass an emissions inspection
• Slightly decreased fuel economy
• Rough idling or engine hesitation in some cases
• Strong exhaust odor due to a potential rich fuel mixture

Most Likely Causes

1. Failed Downstream Oxygen Sensor (Bank 1, Sensor 2) 🔴 High Probability → Shop Oxygen Sensor Oxygen sensors have a finite lifespan (typically 90,000-120,000 miles) and fail from constant exposure to high-temperature exhaust gases and contaminants. It is the most common cause for this code.
   How to confirm: Use a scan tool to monitor the live data for the B1S2 voltage. If it is stuck high (e.g., >0.9V) and does not fluctuate with the engine warm 🎬 Watch: Easy DIY steps to test your oxygen sensor, the sensor is very likely bad. A healthy downstream sensor should show a lazy, slow fluctuation around 0.5V.
   Typical fix: Replace the downstream (post-catalytic converter) oxygen sensor. Penetrating oil and a specialized O2 sensor socket are recommended for removal.
   Est. part cost: $45-$90
2. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness runs under the vehicle and is exposed to road debris, moisture, and heat. Wires can get snagged, melt on the exhaust, or the connector pins can corrode, causing a short to power or an open circuit. 🎬 See this guide on testing sensor wires and identifying circuits
   How to confirm: Visually inspect the entire wiring harness from the O2 sensor to where it enters the cabin. Check the connector for corrosion, bent pins, or loose connections. Test for a short to power in the signal wire using a multimeter.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the connector.
   Est. part cost: $5-$50

Rare But Worth Checking

• Engine Running Rich: While a rich condition can cause a high voltage reading, it will usually be accompanied by other trouble codes related to the fuel system (e.g., leaky fuel injectors, faulty fuel pressure regulator) or the upstream Air/Fuel ratio sensor.
• Blown Fuse: The oxygen sensor's heater circuit is protected by a fuse. If this fuse blows, it can sometimes lead to erratic voltage readings, including a P0138 code. Check the fuse box diagrams for a fuse labeled 'O2 Heater' or similar.
• Faulty Powertrain Control Module (PCM): This is very rare. The PCM should only be considered after all other possibilities, including the sensor and its entire circuit, have been thoroughly tested and ruled out.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0138 is present.
2. Visually inspect the downstream O2 sensor, its connector, and wiring harness for any signs of physical damage, melting, corrosion, or breaks.
3. Check the fuse for the O2 sensor heater circuit in the vehicle's fuse box.
4. Use the scanner to view live data for the 'Bank 1 Sensor 2' voltage. With the engine running and warm, a healthy sensor will show a slow, steady voltage. A faulty sensor triggering P0138 will likely be stuck at a high voltage (above 0.9V, and specifically above 1.27V for the code to set on this vehicle).
5. If the sensor reading is stuck high, the sensor itself is the most likely failure. Proceed with replacement. An O2 sensor socket will make removal much easier.
6. If a new sensor does not fix the issue, perform a circuit test. Check for a short to power on the sensor's signal wire and verify the ground and heater circuits are intact. A Honda-specific test involves checking for voltage between the PCM connector and ground.
7. If the sensor and wiring are confirmed to be good, investigate potential causes of a rich running condition, but this is unlikely without other codes being present.

Parts You'll Likely Need

• Downstream Oxygen Sensor (Bank 1, Sensor 2) (OEM #2011 (3rd Gen): 36532-REZ-A01 | 2012-2014 (4th Gen): 36532-R5A-A01 | 2015-2016 (4th Gen Facelift): 36532-5LA-A01) — This is the component that directly reports the high voltage condition and is the most common point of failure for this code.
  Trusted brands: Denso (OEM Supplier), Bosch, NGK/NTK, Walker
  OEM price range: $70-$150
  Aftermarket price range: $45-$65

Platform-Specific Known Issues

• Generational and Mid-Generation Part Incompatibility: The 2011 (3rd Gen), 2012-2014 (4th Gen), and 2015-2016 (4th Gen Facelift) CR-Vs all use different downstream O2 sensors. The OEM part for 2011 is 36532-REZ-A01, the 2012-2014 model uses 36532-R5A-A01, and the 2015-2016 model uses 36532-5LA-A01 due to the change to the K24W9 engine. Using the wrong part will not work and will cause the code to persist. Always verify with the VIN.
• Aftermarket Sensor Quality: While many aftermarket sensors work well, Honda ECUs can be sensitive. Using a quality brand like Denso (the typical OEM supplier) or NTK is highly recommended to avoid compatibility issues that can cause the P0138 code to return even with a new sensor.

Mechanic-Grade Diagnostic Values

• Secondary HO2S (Sensor 2) Voltage — expected: Slowly fluctuating around 0.45V - 0.7V on a warm, running engine.. Failure: Voltage is stuck high, consistently reading above 0.9V. The PCM will trigger DTC P0138 if the voltage exceeds 1.27V for a set period.
• Secondary HO2S (Sensor 2) Heater Resistance — expected: 10 - 40 Ohms when measured across the two heater wires (often same color) on a disconnected sensor.. Failure: An open circuit (infinite resistance) or a dead short (near zero ohms). A reading far outside the expected range suggests a faulty heater element.

Scan Tool Commands That Help

• Honda HDS (Honda Diagnostic System): Jump SCS line — This function is used during advanced wiring diagnostics. For example, in one test step for P0138, the technician must jump the SCS line before disconnecting PCM connector A to safely test for continuity on the O2 sensor signal wire without setting other codes.

Wiring & Ground Locations

• G101 — Located on the left rear of the engine, typically on the thermostat housing.. This is a primary ground termination point for the ECU (PCM). A poor connection here due to corrosion or looseness can cause erratic sensor readings and numerous, hard-to-diagnose electrical issues, including O2 sensor faults.
• Secondary HO2S 4P Connector — The 4-pin electrical connector attached directly to the downstream oxygen sensor's pigtail.. This is the primary point for visual inspection of corrosion and for performing electrical tests on the sensor side of the circuit, such as checking heater resistance.
• PCM Connector A (50P) / B (49P) — One of the main multi-pin connectors plugged into the Powertrain Control Module (PCM). The specific connector varies by year and engine.. This is where the sensor harness ultimately connects. Advanced diagnostics for an open or shorted wire require disconnecting this connector to test continuity of the signal wire (e.g., pin A47 or B46 depending on model) back to the sensor connector.

OEM Part Supersession History

• 36532-R5A-004 → 36532-R5A-305, then 36532-R5A-A01 — Standard part revision and supplier changes.
  Heads up: These parts are specific to the pre-facelift 4th generation CR-V and are not compatible with 2011 or 2015-2016 models.
• N/A → 36532-5LA-A01 — New part for the updated K24W9 'Earth Dreams' engine.
  Heads up: This part is only for 2015-2016 CR-V models. It will not work on earlier 2011-2014 models.

Model Year Variations Within This Range

• 2015-2016: These model years received a mid-cycle refresh including the K24W9 'Earth Dreams' direct-injection engine and a CVT. They use a different downstream oxygen sensor (P/N: 36532-5LA-A01) than the 2012-2014 models.
• 2012-2014: These models use the K24Z7 engine and have their own specific downstream oxygen sensor (P/N: 36532-R5A-A01).
• 2011: As the last year of the 3rd generation, this model has a different chassis and uses the K24Z6 engine. It requires a unique downstream O2 sensor (P/N: 36532-REZ-A01).

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0141 — O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 2) - Related because the diagnosis steps require checking the fuse for the O2 sensor heater circuit, which shares the same wiring harness and connector.
• P0172 — System Too Rich (Bank 1) - Related because a strong exhaust odor due to a potential rich fuel mixture is a known symptom that can trigger a high voltage reading on the downstream sensor.
• P0137 — O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2) - The electrical opposite of P0138, often caused by the same damaged wiring harness, corroded connector pins, or an open circuit.
• P0133 — O2 Sensor Circuit Slow Response (Bank 1, Sensor 1) - Related because a skewed or failing upstream sensor can cause the downstream sensor to report an error, as noted in diagnostic discussions.
• P0420 — Catalyst System Efficiency Below Threshold (Bank 1) - Related because the downstream O2 sensor monitors the catalytic converter, and a failure in this sensor can impact emissions inspections and catalyst monitoring.

Frequently Asked Questions