2007 Nissan Frontier Check Engine Light On: P0300, P0021 (Bank 2 & 3), P0459 - Persistent Misfire and EVAP Issues
My 2007 Nissan Frontier has had a recurring check engine light issue that started randomly and now stays on continuously. Initially, I took it to AutoZone, which suggested an evaporative emissions leak—replacing the gas cap resolved this temporarily. However, after just 65 miles, the problem returned. The OBD2 scan revealed codes P0300 (random misfire), P0021 (Variable Valve Timing - Bank 2), and P0452 (EVAP system pressure sensor issue). I replaced the EVAP valve as recommended, but last week the truck began running rough at idle. I replaced all spark plugs with Autolite ones; however, one broke during installation. Afterward, the idle became slightly high. I’ve since changed the oil and inspected connections. The vehicle runs normally when the battery is disconnected—indicating a possible electrical or sensor-related issue that only manifests under idle conditions. The misfire (P0300) persists even after plug replacement. I suspect the P0021 codes are more critical, as they relate to VCT (Variable Cam Timing), and oil quality/condition may be contributing. I’ve checked all electrical connectors, including those for the EVAP canister—some appear damaged or loose. I’m now looking into replacing them, though local auto parts stores like NAPA don’t carry the correct connectors. I’ve also been advised to check if Autolite plugs are compatible with my vehicle (they may not be OEM). The oil change helped temporarily, but the root cause remains unclear. Any insights on diagnosing P0300 in conjunction with P0021 and P0452? Is there a known issue with 2007 Frontier VCT systems or EVAP sensors under idle conditions?
P0021 refers to Variable Cam Timing (VCT) on Bank 2—engine oil quality and quantity are common causes. Check if the oil is within recommended levels and has not degraded. Inspect the electrical connector for tightness; ensure there's a solid 12V reading at KOEO (Key On, Engine Off). A failed VCT valve often shows signs of sludge or varnish buildup inside the valve body. As a temporary fix, consider adding one 16 oz bottle of 'Risolone' oil detergent to help break down sludge. Always follow manufacturer guidelines when using additives. P0452: EVAP Control System Pressure Sensor—verify the connector at the EVAP canister is securely attached. Have you recently performed any fuel system work? If so, that could be a contributing factor. Use a digital multimeter (DVOM) and wiring diagram to confirm proper voltage and ground connections. P0300: You used Autolite plugs—these are not OEM for this model. Confirm if NGK or other OEM brands are recommended in the owner’s manual. Misfires may stem from poor ignition components, especially if spark plug integrity is compromised.