P0A2D🔧 Hybrid system (drive motor)Stop and fix promptly

P0A2D: Drive Motor "A" Temperature Sensor Circuit High (Meaning, Causes, Fixes)

Reviewed 2026-10-24 · Based on 3 cited source(s)

What P0A2D means

Hybrid drive motors have a temperature sensor (a thermistor) built in. Its resistance drops as the motor gets hotter, and the hybrid computer reads the resulting voltage to know the motor temperature and limit the load before it overheats. P0A2D means that voltage is reading too high. Toyota's 2004 Prius repair manual says the HV control computer sets P0A2D (information code 249) for an open circuit or short to power in the motor temperature sensor No. 1 circuit, and a scan tool will then show the motor temperature stuck at -50 C (-58 F). Ford's 2018 C-Max Hybrid manual says the transmission control module sets P0A2D when the motor temperature (MCT) circuit is above or below a calibrated threshold. RepairPal says the sensor is built into the hybrid motor assembly and the engine computer sets the code when it detects a failure in the sensor circuit.

Severity: can I keep driving?

Stop and fix promptly

Get it checked soon. RepairPal rates P0A2D as Urgent and says the high-voltage system may not operate. The hybrid computer uses this sensor to limit the load on the drive motor so it doesn't overheat, so a bad reading takes away that protection. The check engine light will also fail an emissions inspection.

Common symptoms

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

  1. An open circuit or short to power in the wiring or connector between the motor temperature sensor and the hybrid control computer (Toyota 2004 Prius manual; Ford C-Max manual lists open or shorted MCT and MCTRTN circuits)
  2. A failed temperature sensor inside the hybrid drive motor, which means replacing the motor assembly (Toyota 2004 Prius manual; RepairPal lists high-voltage motor failure)
  3. A faulty hybrid control computer (Toyota 2004 Prius manual) or transmission control module (Ford C-Max manual)
  4. A damaged transmission on the Ford C-Max (Ford C-Max manual)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

  1. Safety first: hybrids carry high voltage. Never unplug orange cables or open the inverter, motor or hybrid battery yourself.
  2. Read every stored code with a scan tool that can read the hybrid system, and write down any other codes before clearing anything.
  3. If your scan tool shows live data, check the drive motor temperature. Toyota's manual says a reading of -50 C (-58 F) points to an open circuit or short to power, while a normal-looking reading means the fault may be intermittent.
  4. Look for obvious damage, corrosion or loose connections at the low-voltage sensor connectors near the transaxle, but leave the testing to a shop if you aren't sure which wires are high voltage.

Typical fixes

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

  • Any work near the hybrid transaxle, inverter or orange high-voltage cables
  • You need a scan tool that reads hybrid live data and codes (Toyota Techstream, Ford IDS or equivalent)
  • The car won't go into READY mode or the hybrid system shuts down
  • Ask a dealer whether your hybrid system warranty still covers the motor or transaxle before paying for a replacement

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0A2D serious?

Yes. RepairPal rates it Urgent and says the high-voltage system may not operate. The hybrid computer relies on this sensor to protect the drive motor from overheating, so get it diagnosed soon.

Can I replace just the motor temperature sensor?

Usually not. Toyota's 2004 Prius repair manual says motor temperature sensor No. 1 isn't available as a separate service part, so if the sensor has failed the hybrid vehicle motor assembly has to be replaced. Check the wiring and connectors first, since those are much cheaper to fix.

What's the difference between P0A2B, P0A2C and P0A2D?

All three are for the same drive motor temperature sensor. On the 2004 Prius, Toyota uses P0A2C for a short to ground (the scan tool shows 205 C or 401 F), P0A2D for an open circuit or short to power (it shows -50 C or -58 F), and P0A2B for a sensor malfunction or performance problem, where the fix is replacing the motor.

Do the sources agree on P0A2D?

Mostly, with some differences in detail. Toyota's manual ties P0A2D specifically to an open circuit or short to power, while Ford's C-Max manual uses broader wording (the circuit is above or below a threshold) and lists shorts to ground as a possible cause too. Toyota has the HV control computer set the code, Ford has the transmission control module set it, and RepairPal says the engine computer (PCM) sets it. RepairPal lists high-voltage motor failure as the common cause, while both factory manuals start with the wiring.

How much does it cost to fix P0A2D?

None of the sources give a repair cost. It can range from fixing a wire or connector to replacing the hybrid motor or transaxle assembly, so get a proper diagnosis and ask about hybrid warranty coverage first.

Sources

  1. RepairPal: P0A2D Drive Motor "A" Temperature Sensor Circuit High (rated Urgent)
  2. Toyota 2004 Prius Repair Manual (RM1075U): DTC P0A2C/247 and P0A2D/249 Drive Motor "A" Temperature Sensor Circuit Low/High (hosted copy)
  3. Ford 2018 C-Max Hybrid Service Manual: DTC P0A2D Drive Motor A Temperature Sensor Circuit High (hosted copy on LEMON Manuals)

Last reviewed 2026-10-24. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.