Crankshaft Position Sensor A Circuit High Input
The crankshaft position sensor circuit is detecting a voltage that is higher than the PCM expects, preventing the engine control module from accurately reading engine speed and timing. This sensor is critical for engine start and operation, and a high-input fault typically results in a no-start condition or severe running problems.
What You Might Notice
- Engine will not start or fails to crank
- Tachometer does not register engine RPM
- Engine stalls immediately after starting
- Repeated no-start condition after initial startup
- Check Engine Light illuminated
Most Common Causes
- 1
Defective Crankshaft Position Sensor
The CKP sensor itself may have failed internally, causing it to send an abnormally high voltage signal to the PCM. This is the most common cause of this fault code.
- 2
Corroded or Wet Sensor Connector
Moisture or corrosion at the CKP sensor connector can cause resistance changes that result in high voltage readings. Connector damage prevents proper signal transmission.
- 3
Open or Shorted Wiring to CKP Sensor
Damaged wiring harness, broken conductors, or short circuits between the sensor and PCM can create abnormal voltage levels that trigger this code.
- 4
Alternator Overcharging or PCM Malfunction
Alternator overcharging can affect PCM voltage regulation, or the PCM itself may have a programming error or internal failure causing incorrect sensor signal interpretation.
How to Diagnose It
- 1
Check Defective Crankshaft Position Sensor — The CKP sensor itself may have failed internally, causing it to send an abnormally high voltage signal to the PCM. This is the most common cause of this fault code.
- 2
Check Corroded or Wet Sensor Connector — Moisture or corrosion at the CKP sensor connector can cause resistance changes that result in high voltage readings. Connector damage prevents proper signal transmission.
- 3
Check Open or Shorted Wiring to CKP Sensor — Damaged wiring harness, broken conductors, or short circuits between the sensor and PCM can create abnormal voltage levels that trigger this code.
- 4
Check Alternator Overcharging or PCM Malfunction — Alternator overcharging can affect PCM voltage regulation, or the PCM itself may have a programming error or internal failure causing incorrect sensor signal interpretation.
How to Fix It
- 1
Replace Crankshaft Position Sensor
Disconnect the sensor connector, remove the mounting bolt, and install a new CKP sensor in the same location. Reconnect the electrical connector and clear the code to verify the repair.
- 2
Inspect and Repair CKP Sensor Connector
Remove the connector from the CKP sensor and inspect for corrosion, moisture, or bent pins. Clean with electrical contact cleaner, dry thoroughly, or replace the connector if damage is found.
- 3
Check and Repair Wiring Harness
Visually trace the CKP sensor wiring from the sensor to the PCM, looking for breaks, pinches, or corrosion. Repair damaged wiring with appropriate connectors or replace the entire harness if necessary.
- 4
Test Alternator Output and PCM Function
Use a multimeter to verify alternator output voltage is within specification (typically 13.5-14.5V). If high, repair the alternator. If voltage is normal, consult a dealer for PCM reprogramming or replacement.
Need a deeper diagnosis?
Search for related repair guides or browse by system.