Mercedes GLA diesel engine rail pressure sensor problem

Sounds like a faulty rail pressure sensor alright. I had a similar issue with my old Vauxhall Astra, though it was the camshaft position sensor throwing codes. Symptoms were almost identical check engine light, rough idle, and limp mode kicking in. Have you checked the wiring to the pressure sensor? Sometimes a loose connection or damaged wire can cause a bad sensor signal. Worth a quick look before replacing the sensor itself.

Thank you for your response. Regarding your suggestion to examine the wiring to the pressure sensor, could you provide more specific guidance on how to effectively conduct this inspection? I am not particularly experienced in automotive diagnostics, and would appreciate any detailed instructions you might offer.

Yeah, no problem. Basically, just locate the rail pressure sensor on the fuel rail usually somewhere near the injectors. Then, carefully inspect the wiring harness and connector leading to the sensor. Look for any signs of damage frayed wires, cracked insulation, or corrosion in the connector. Give the wires a gentle wiggle while the engine is running carefully to see if the engine stumbles or the sensor reading changes. If you see anything obvious, that could be your problem. If not, it's likely the sensor itself is toast. I ended up just taking my Astra to a shop after checking the wiring since I didn't have the right tools to test the sensor output. They confirmed it was a bad sensor.

I appreciate the detailed explanation and the suggestion to inspect the wiring harness. While I did perform a cursory examination, I did not observe any readily apparent damage. Consequently, I proceeded to have the vehicle assessed by a qualified technician. As you suspected, the rail pressure sensor was indeed found to be defective. The replacement cost, including labor, amounted to 240€. The issue has now been resolved. Thank you again for your assistance.