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 a sensor in the car's engine is reading too high when the car is slowing down. It's like the car's nose is sniffing too much air when it shouldn't be.
The P1242 code is triggered when the Engine Control Module (ECM) detects that the signal from the secondary upstream manifold air pressure sensor is higher than expected during a deceleration phase.
The manifold air pressure sensor measures the pressure inside the intake manifold. During deceleration, this pressure should decrease. If the sensor reads a pressure that is too high, it indicates a possible issue with the sensor itself, the wiring, or a related component that affects the intake manifold pressure.
• Check Engine Light illuminated
• Poor engine performance
• Increased fuel consumption
• Faulty manifold air pressure sensor
• Wiring issues such as shorts or open circuits
• Vacuum leaks in the intake manifold
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Inspect the manifold air pressure sensor and its wiring for damage.
• Check for vacuum leaks in the intake manifold.
• Replace the manifold air pressure sensor if faulty.
• Repair or replace damaged wiring.
• Fix any vacuum leaks in the intake manifold.
• OBD-II scanner
• Multimeter
• Vacuum gauge
$100 - $300
Moderate
• Toyota Camry
• Honda Accord
• Ford Focus
• Regularly inspect and maintain engine sensors.
• Check for vacuum leaks during routine maintenance.
• Ensure wiring is intact and free from corrosion.
Sensor Issue
• Avoid driving aggressively until the issue is resolved.
• Have the vehicle inspected by a professional mechanic.
Check with your vehicle's manufacturer for specific warranty coverage on sensors.
This code has been associated with sensor failures and wiring issues in various models over the years.
Moderate – It's important to address this issue soon to prevent further engine performance problems.
Driving with a faulty sensor may lead to increased emissions and reduced fuel efficiency.
• Engine at operating temperature
• Vehicle in deceleration mode
The manifold air pressure sensor is typically located on the intake manifold near the throttle body.
Q: Can I drive with a P1242 code?
A: It's possible to drive short distances, but it's best to get it fixed soon to avoid further issues.
Q: How do I reset the Check Engine Light after fixing the issue?
A: Use an OBD-II scanner to clear the code, or disconnect the battery for a few minutes.
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