P0A42: Drive Motor A Position Sensor Circuit High

P0A42 is the counterpart to P0A41: a resolver line of motor A reads above its allowed range. Typical triggers are a sine, cosine or excitation wire shorted to a supply voltage, or an open coil whose line is pulled up by the bias resistors of the input circuit, which drives the converter into clipping. Kia covers it in the same Optima Hybrid 2011-13 bulletin as P0A41: intermittent MIL or hybrid service lamp, fixed by inspecting the HPCU-to-motor sub-harness for internal shorts and pin fit. Bosch patents explain why clipping alone is not enough and how the line offset reveals a short to supply or an open line. P0A3F is the general circuit fault. Expect a warning lamp and reduced or no electric drive.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

Intermittent MIL or hybrid service lamp
Electric drive disabled or vehicle not ready
Reduced power until the fault clears

Most likely causes

Resolver wire shorted to a supply voltage inside the sub-harness (Kia Optima Hybrid)
Open sine or cosine line pulled high by the input circuit
Poor pin fit or corrosion at the resolver connectors
Faulty resolver input stage in the motor control unit

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0A42 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
A: Hybrid or air and fuel
42: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0A42?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0A42?

The most common causes are: resolver wire shorted to a supply voltage inside the sub-harness (Kia Optima Hybrid); open sine or cosine line pulled high by the input circuit; poor pin fit or corrosion at the resolver connectors.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.