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 getting a signal from a sensor that measures air pressure in the engine, and the signal is too high. It's like the sensor is saying there's too much air pressure, even if there might not be.
The P1238 code is triggered when the Engine Control Module (ECM) detects a high voltage signal from the secondary upstream manifold air pressure sensor, indicating that the sensor is reporting higher pressure than expected.
The secondary upstream manifold air pressure sensor is responsible for measuring the air pressure in the intake manifold. The ECM uses this data to optimize the air-fuel mixture for efficient combustion. A high circuit signal indicates that the sensor is reporting an abnormally high pressure, which can affect engine performance and emissions.
• Check Engine Light illuminated
• Poor engine performance
• Increased fuel consumption
• Faulty manifold air pressure sensor
• Wiring issues such as short circuits or open circuits
• Faulty ECM
ECM: Engine Control Module, the computer that controls engine functions.
OBD-II: On-Board Diagnostics, a system that monitors vehicle performance and emissions.
• Use an OBD-II scanner to confirm the code.
• Inspect the manifold air pressure sensor and its wiring for damage.
• Test the sensor's voltage and compare it to manufacturer specifications.
• Replace the manifold air pressure sensor if faulty.
• Repair or replace damaged wiring.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Screwdriver set
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain sensor wiring.
• Keep the intake system clean.
• Use high-quality fuel to prevent buildup.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Avoid driving the vehicle if performance issues are severe.
Check with your vehicle manufacturer for warranty coverage on sensors and related components.
This code has been reported in vehicles with high mileage or those that have experienced engine modifications or intake system changes.
Moderate – Addressing this issue is important to maintain engine performance and fuel efficiency.
Driving with a faulty air pressure sensor can lead to increased emissions and potential safety risks due to poor engine performance.
• Engine running
• Warm engine temperature
The manifold air pressure sensor is typically located on the intake manifold near the throttle body.
Q: Can I drive with a P1238 code?
A: It's not recommended to drive for long periods with this code, as it can affect engine performance and fuel efficiency.
Q: How do I reset the Check Engine Light after fixing the issue?
A: You can use an OBD-II scanner to clear the code, or the light may turn off automatically after a few driving cycles if the issue is resolved.
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