A 2019 Porsche Panamera came into a shop with an illuminated check engine light, driving perfectly on the road test but storing P24D600 and P24D800 in the engine control module. The technician noted zero driveability issues. These codes point directly to the EVAP System Pressure Sensor B, a component designated by Porsche as the G950 sensor.
Our own data ranks an internal transducer failure of the G950 sensor as the most likely cause, sitting at a 75 percent probability for this specific vehicle and fault combination.
The G950 sensor failure mechanism
On the CXTA 3.0L V6 Turbo engine, the G950 sensor measures vapor pressure in the purge line downstream of the N80 purge regulator valve. The engine control module provides a 5.0-volt reference and monitors the return signal via an internal pull-up resistor circuit.
When the sensor suffers an internal open circuit, a broken bond wire, or a piezo-resistive diaphragm failure, the signal line is pulled up to the 5.0-volt ceiling. A reading above 4.8 volts triggers the P24D800 circuit high code. Because the signal remains locked at maximum voltage and fails to fluctuate during active N80 purge valve modulation, the module logs P24D600 for a range and performance plausibility failure. The recommended diagnostic path starts with live data monitoring of the sensor voltage and absolute pressure, followed by a signal circuit grounding bypass test.
Checking the ground return circuit
A break or high electrical resistance in the sensor ground return circuit can also force the signal voltage to float to the 5.0-volt reference ceiling. This harness routing crosses the Bank 1 valve cover adjacent to the turbocharger and exhaust manifold heat shields.
Mechanical engine vibrations and severe thermal cycles can cause pin fretting at the harness connector or continuous circuit open conditions on Pin 2 back to the engine control module. If the ground circuit has open resistance, the internal circuitry cannot complete its loop. A digital multimeter check of the reference supply voltage and a harness wiggle test while logging live sensor voltage will isolate this issue.
Ruling out mechanical EVAP faults
The G950 pressure sensor sits in series with the N80 EVAP Canister Purge Regulator Valve. If the N80 valve sticks mechanically closed or develops internal seat leakage from fuel varnish, the vacuum pulses expected during purge cycles will not develop across the sensor. The engine module sees that the commanded purge flow does not create the anticipated pressure drop, flagging P24D600.
Additionally, the EA839 engine uses a dual-path purge vent line assembly. At idle, vapors are drawn into the intake manifold behind the throttle valve. Under boost, vapors are directed into the turbocharger compressor inlet via internal one-way check valves. If an internal check valve fails open, turbocharger boost pressure up to 20 psi can backfeed directly into the G950 sensor cavity. This overpressurization causes the sensor output to spike far beyond the expected atmospheric operating envelope.
Next steps for your bay
Checking live sensor data and verifying the 5.0-volt reference circuit are the fastest ways to separate a dead G950 transducer from a harness issue or a mechanical N80 valve failure. If you see this pair of codes on a 3.0T Panamera in your shop, we would love to hear which component ended up being the culprit.
