Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer is detecting a problem with the heater part of an oxygen sensor. It's like the sensor isn't getting enough power to heat up properly.
The oxygen sensor helps the car's computer know how much fuel to use. The heater in the sensor helps it work better when the engine is cold. If there's low voltage, the heater might not work right.
The P1138 code indicates that the voltage in the heater circuit of the oxygen sensor located on Bank 1, Sensor 2, is lower than expected. This can affect the sensor's ability to accurately measure the oxygen levels in the exhaust, leading to poor fuel mixture control.
• Check Engine Light is on
• Poor fuel economy
• Rough idle
• Increased emissions
• Faulty oxygen sensor
• Damaged wiring or connectors in the heater circuit
• Blown fuse for the O2 sensor heater
• Faulty powertrain control module (PCM)
O2 Sensor: Oxygen sensor, a device that measures the amount of oxygen in the exhaust gases.
PCM: Powertrain Control Module, the car's main computer that controls engine and transmission functions.
• Use an OBD-II scanner to confirm the code
• Inspect the oxygen sensor and its wiring for damage
• Check the fuse for the O2 sensor heater
• Measure the voltage in the heater circuit
• Replace the faulty oxygen sensor
• Repair or replace damaged wiring or connectors
• Replace the blown fuse
• Reprogram or replace the PCM if necessary
• OBD-II scanner
• Multimeter
• Wrench set
$100 - $300
Moderate
• Nissan Altima
• Infiniti G35
• Nissan Maxima
• Regularly inspect and maintain the vehicle's exhaust system
• Ensure proper electrical connections
• Use high-quality fuel
Sensor Issue
• Get the issue diagnosed and repaired promptly to avoid further damage.
• Do not ignore the Check Engine Light.
Oxygen sensors may be covered under emissions warranty. Check with your vehicle manufacturer.
This code is common in vehicles with aging oxygen sensors or electrical issues in the sensor circuit.
Moderate – Should be addressed soon to avoid potential damage to the catalytic converter.
Ignoring this issue may lead to increased emissions, which can be illegal in some areas.
• Engine at operating temperature
• Use of a diagnostic scanner
The oxygen sensor is located in the exhaust system, typically after the catalytic converter on Bank 1.
Q: Can I drive with a P1138 code?
A: You can drive, but it's best to fix it soon to avoid further issues.
Q: How does an O2 sensor heater work?
A: It heats the sensor to help it get accurate readings quickly, even when the engine is cold.
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Fitment Required · Vehicle-fitment part
Relevant when the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
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Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.