Hey guys, let's dive deep into the nitty-gritty of the 2003 Infiniti G35 camshaft position sensor. If your G35 is acting up, throwing codes, or just generally feeling sluggish, this little guy might be the culprit. We're going to break down what it does, what happens when it goes bad, and how you can get it sorted. It's a pretty crucial component for your engine's performance, so understanding its role is key.

What Does the Camshaft Position Sensor Do?

The camshaft position sensor (CMP sensor) is a vital piece of the puzzle in your 2003 Infiniti G35's engine management system. Think of it as the engine's eyes for the camshaft. Its primary job is to tell the Engine Control Unit (ECU) the precise position of the camshaft lobes. This information is absolutely critical because it helps the ECU determine when to inject fuel into the cylinders and when to fire the spark plugs. Without accurate camshaft position data, the ECU is essentially flying blind, leading to all sorts of performance issues. The sensor works by detecting a specific pattern on the camshaft (often a reluctor wheel with teeth or notches). As the camshaft rotates, these teeth pass by the sensor, interrupting a magnetic field or changing a resistance. The ECU interprets these changes as signals indicating the camshaft's position. This data is then synchronized with the crankshaft position sensor (CKP sensor), which tells the ECU the position of the crankshaft. By combining these two signals, the ECU can pinpoint the exact timing for ignition and fuel injection, optimizing engine performance, fuel efficiency, and emissions. It's a delicate dance, and the CMP sensor is a key dancer ensuring everything happens at the right moment.

Common Symptoms of a Bad Camshaft Position Sensor

So, how do you know if your 2003 Infiniti G35 camshaft position sensor is on its last legs? Well, there are a few telltale signs you should look out for. The most common symptom is a check engine light (CEL) illuminating on your dashboard. This is often accompanied by specific diagnostic trouble codes (DTCs) related to camshaft position sensor circuit malfunction or performance. P0340 and P0345 are pretty common codes you might see. Beyond the CEL, you might experience engine performance issues. This can manifest as rough idling, stalling, especially when the engine is hot, and difficulty starting the engine. Sometimes, the car might crank but not start at all, or it might start but die shortly after. You might also notice a hesitation or stumbling when you accelerate. This is because the ECU isn't getting the correct timing information, so it can't precisely control fuel delivery and ignition. In some cases, you could even experience a decrease in fuel economy. While not as dramatic as stalling, inefficient engine timing due to a faulty sensor can lead to the engine burning more fuel than it needs to. It's a progressive thing, often starting subtly and becoming more pronounced as the sensor continues to degrade. Pay attention to how your G35 is running – any unusual behavior could be a clue.

Rough Idling and Stalling

One of the most frustrating symptoms of a failing 2003 Infiniti G35 camshaft position sensor is the dreaded rough idling and stalling. When this sensor isn't providing accurate data to the ECU, the engine's timing gets thrown off. The ECU relies on this sensor to know exactly when the intake and exhaust valves are opening and closing, which is critical for smooth combustion. If the ECU is getting incorrect signals, it might try to inject fuel or fire the spark plug at the wrong time. This can lead to an uneven burn in the cylinders, causing the engine to shake or vibrate excessively when it's idling. It's like the engine is sputtering or misfiring, even if there isn't a specific misfire code being thrown yet. The problem often gets worse when the engine is warm because electronic components can be more sensitive to heat. So, you might notice your G35 idling smoothly when it's cold, but then start to run rough and even stall as it reaches its operating temperature. Stalling can happen at idle or even when you're coming to a stop, which can be pretty dangerous. The ECU might also struggle to maintain a stable idle speed, causing the RPMs to fluctuate wildly. If you're finding yourself constantly having to restart your car or dealing with an engine that feels like it's about to give up the ghost when you're stopped, your camshaft position sensor should definitely be on your suspect list.

Difficulty Starting or Cranking

Another major red flag for a compromised 2003 Infiniti G35 camshaft position sensor is difficulty starting or cranking. This is because the camshaft position sensor works hand-in-hand with the crankshaft position sensor to give the ECU a clear picture of the engine's rotational position. The ECU uses this combined information to initiate the fuel injection and ignition sequence. If the CMP sensor is faulty, it might send intermittent or incorrect signals, or no signal at all. In the worst-case scenario, the ECU might not receive any information about the camshaft's position. Without this crucial data, the ECU simply doesn't know when to tell the injectors to spray fuel or the spark plugs to fire. This can result in the engine cranking endlessly but never actually firing up – the classic