Faulty exhaust bypass valve position sensor or its internal circuitry; Wiring damage such as chafed, corroded, or disconnected wires between the sensor and the PCM; Sticking or binding exhaust bypass valve mechanism due to carbon buildup or mechanical wear; Failed exhaust heat exchanger assembly, including a stuck valve actuator; Corroded or loose electrical connectors at the sensor or PCM; PCM software calibration issue or internal fault (less common)

DTC codes / P2Cxx · Hybrid propulsion / P2C23

P2C23Exhaust Heat Exchanger Exhaust Bypass Valve A Position Sensor Performance

P2C23 is a generic powertrain code indicating that the powertrain control module (PCM) has detected an out-of-range or erratic signal from the exhaust bypass valve position sensor, which is part of the exhaust heat exchanger assembly. The PCM compares the sensor's reported valve position against the commanded position and sets this code when the correlation falls outside the expected range for a calibrated time period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine performance or power, especially during demanding driving conditions
Poor fuel economy due to incorrect exhaust flow management
Inability to enter or maintain certain drive modes that rely on exhaust heat management
In rare cases, a burning smell or visible exhaust leaks near the heat exchanger
Intermittent operation of the exhaust bypass valve, causing fluctuating performance

Common causes, most likely first

Faulty exhaust bypass valve position sensor or its internal circuitry
Wiring damage such as chafed, corroded, or disconnected wires between the sensor and the PCM
Sticking or binding exhaust bypass valve mechanism due to carbon buildup or mechanical wear
Failed exhaust heat exchanger assembly, including a stuck valve actuator
Corroded or loose electrical connectors at the sensor or PCM
PCM software calibration issue or internal fault (less common)

How to diagnose and fix it

Perform a visual inspection of the exhaust bypass valve, sensor, and wiring for obvious damage or corrosion
Use a scan tool to retrieve all stored codes and freeze-frame data, then clear codes and test-drive to see if P2C23 returns
Check the sensor's reference voltage and ground circuits with a multimeter to rule out wiring faults
Command the bypass valve open and closed with a bidirectional scan tool while monitoring the position sensor signal for smooth operation
Remove and inspect the bypass valve for carbon buildup or mechanical binding; clean or replace as necessary
Replace the exhaust bypass valve position sensor if the signal is erratic or out of specification
If all else fails, reprogram the PCM with the latest calibration or replace it after confirming all other components are good

Before replacing the heat exchanger assembly

A sticking bypass valve is often the root cause, and cleaning the valve mechanism can resolve the code without replacing expensive parts.
The position sensor is frequently misdiagnosed as the sole culprit when the actual problem is a binding valve that prevents the sensor from reading correctly.
Wiring harness damage near the exhaust heat exchanger is common due to heat exposure, so always inspect the harness routing and insulation.
This code can be set by a PCM calibration issue, so check for technical service bulletins (TSBs) before condemning hardware.
After repairs, a relearn or adaptation reset may be required for the PCM to correctly interpret the new sensor signals.

Can I keep driving with P2C23?

You can generally continue driving with this code, but avoid aggressive acceleration or heavy loads until it is repaired, as the bypass valve may not function correctly and could affect emissions or performance. If you notice severe power loss or unusual noises, have the vehicle inspected promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.