What P0A40 means
P0A40 means the resolver of motor A still delivers a signal, but its quality is poor or implausible.
How the engine computer detects it
GM calls this a degraded signal: the sine or cosine value exceeds 4.0 V, judged within 0.2 to 0.4 s of a 2 s window (Type A, one trip in 2016; Type B, two trips on the 2013 mild hybrid). Mitsubishi (2023 Outlander PHEV front motor) sets it when sine or cosine leaves the 2.1 to 2.9 V band for 0.17 s. Audi lists P0A4000 with an implausible signal on the A7 and Q5 e quattro and replaces rotor position sensor G713 after checking gold-plated connector pins; Bentley pairs it with P0C5100/P0C5B00 and inspects connectors for pin drag. P0A3F is the hard signal loss. Expect a drive system warning or no start.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Drive system fault message in the instrument cluster
- Vehicle cannot be started or will not enter ready mode
- Electric drive disabled or torque jerks while driving
Common causes
- Rotor position sensor (resolver) delivering a degraded signal, e.g. Audi G713 Most likely
- Worn, loose or contaminated contacts in the resolver connectors (Audi, Bentley) Most likely
- Sensor wires pinched or misrouted on the transmission housing after a repair Possible
- Faulty resolver evaluation in the inverter/motor control module Less likely
How to diagnose P0A40
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: drive motor a, rotor position sensor, resolver, wiring harness.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- A
- Hybrid and electric propulsion
- 40
- Specific fault
Questions drivers ask
Can I drive with code P0A40?
If the car drives normally, drive gently to a shop that services hybrids. If it shows a hybrid system warning, loses power or won't go into Ready, pull over and have it towed. Never touch orange high-voltage cables.
Will my car pass an emissions inspection with P0A40?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.