P0CDA: Drive Motor A Position Sensor Circuit C
What to do
If channel A and channel B faults are stored alongside this one, this is the likely cause of all three rather than a third failure — it is what drives the sensor, so losing it silences the other two. Worth saying, because three codes look like a dead sensor and this may be one connector.
What this code means
A third position sensor circuit on drive motor A has a fault.
Channels A and B are at P0C50, where the family's argument lives: they are the sine and cosine halves of one measurement rather than two sensors, and either alone is ambiguous.
A third circuit is usually not a third output but the other half of how a resolver works. These sensors are not passive: they have to be driven. An excitation winding is fed an alternating signal, the rotor modulates it, and the two output windings return it shaped by the rotor's angle. Without excitation there are no outputs at all — so a fault here can silence channels A and B while both are perfectly healthy.
Which gives a useful reading rule: this code appearing alongside A and B faults is likely the cause of them, not a third coincidence. On designs using a digital encoder rather than a resolver the third circuit is more often an index or reference channel, and the same logic applies — it is the shared thing, so suspect it first when its siblings are complaining.
Likely causes
Start here
- Faulty motor position sensor · specialist
- Corroded or loose connector · easy
Less common
- Chafed harness between transaxle and inverter · specialist
- Failed sensor reference voltage supply · moderate
Symptoms
Components involved
Information, not instruction
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Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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