What it means
Same as P242A with intermittent or erratic signal. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The Bank 1 Sensor 3 exhaust gas temperature sensor measures exhaust temperature at its location in the Bank 1 exhaust. The control module sets P242E when that sensor’s signal changes erratically or drops out intermittently, often due to a loose connector or wiring that moves against a vibrating part.
Common causes
Most likely first.
- Intermittent contact at connector
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check-engine light on
- Intermittent reduced power or limited regeneration, if enabled by the vehicle
How to diagnose it
- Record freeze-frame data and review Bank 1 Sensor 3 live data and fault history for sudden dropouts or jumps.
- With the exhaust cool, inspect the Sensor 3 connector for loose fit, corrosion, moisture, or pins pushed back into the connector body.
- Inspect the harness routing for chafing or contact with vibrating or hot components, especially near the sensor.
- Monitor the sensor reading while carefully moving the accessible harness and connector to look for dropouts, following the manufacturer’s safety procedure.
- If the wiring remains stable, test the sensor and circuit under the manufacturer’s procedure and specifications.
Common fixes
- Secure a loose Bank 1 Sensor 3 connector or repair its terminals.
- Repair chafed wiring and route it away from hot or vibrating parts.
- Replace a sensor that intermittently drops out despite a sound connection.
- Repair a verified module-side circuit fault.
Can I keep driving?
Use caution and avoid heavy loads if the fault causes intermittent reduced power or exhaust warnings. A dropping temperature signal can interrupt regeneration or exhaust protection and may lead to further after-treatment problems.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.