Nissan Xterra V6-3.3L P0328 and P0171 Trouble Codes: Detonation, Poor Fuel Economy, and A/C Issue After Knock Sensor Replacement
Hello everyone, I recently had my Nissan Xterra V6-3.3L diagnosed and found two pending trouble codes: P0328 and P0171. I replaced the knock sensor as recommended, but the problem persists. My vehicle still exhibits engine detonation and significantly increased fuel consumption. More recently, I noticed that both trouble codes remain active, and when I turn on the heater, the A/C system activates unexpectedly — which is not normal behavior for my vehicle. Has anyone else experienced this combination of symptoms with these specific OBD2 codes? What are the possible root causes and solutions? Any insights or troubleshooting steps would be greatly appreciated. Thank you in advance! Best regards, A Nissan Xterra Owner
Start by addressing P0171 first — it indicates a lean air-fuel mixture, which can be caused by issues like vacuum leaks, faulty oxygen sensors, or clogged fuel injectors. Check the engine's intake system and ensure all hoses are secure. Refer to this forum’s detailed troubleshooting posts for common causes and fixes related to P0171 in Nissan Xterra V6-3.3L models.