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, which helps control the engine, found something unusual when it checked how fast the car is going. It's like when your video game console checks if the game is running smoothly and finds a glitch.
The control module performs a self-test to ensure that all systems, including speed monitoring, are functioning correctly. If it detects an anomaly, it triggers the P1604 code.
The P1604 code is set when the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects an issue during its self-test routine, specifically related to speed monitoring. This can involve discrepancies in speed sensor readings or internal control module errors.
• Check Engine Light is on
• Erratic speedometer readings
• Poor engine performance
• Faulty speed sensor
• Wiring issues in the speed sensor circuit
• Malfunctioning ECM/PCM
ECM: Engine Control Module
PCM: Powertrain Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the P1604 code.
• Inspect the speed sensor and its wiring for damage.
• Test the ECM/PCM for proper operation.
• Replace the faulty speed sensor.
• Repair or replace damaged wiring.
• Reprogram or replace the ECM/PCM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Toyota Camry
• Honda Accord
• Ford F-150
• Regular maintenance checks
• Ensure wiring is intact and secure
• Update ECM/PCM software as recommended
Engine Performance
• Avoid driving at high speeds until the issue is resolved.
• Have a professional mechanic inspect the vehicle.
Check with your vehicle manufacturer for warranty coverage on the ECM/PCM.
The P1604 code has been commonly associated with vehicles that experience intermittent speed sensor failures or ECM/PCM software glitches.
Moderate – While the vehicle may still be drivable, it is important to address this issue to prevent further complications.
Driving with a malfunctioning speed sensor can lead to inaccurate speed readings, which may result in unsafe driving conditions.
• Engine running
• Vehicle in motion
The speed sensor is typically located on the transmission or differential housing.
Q: Can I drive with a P1604 code?
A: It's possible, but not recommended as it may lead to inaccurate speed readings and affect vehicle performance.
Q: How do I reset the P1604 code?
A: You can reset the code using an OBD-II scanner, but it's important to fix the underlying issue to prevent it from returning.
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