Hello everyone! I'm a newcomer to the forum, sending greetings from Ukraine, and I want to express my sincere gratitude for the support and help in the fight against Russia. We are truly thankful.

My father and I own a 2007 Nissan X-Trail, and we've had it since 2016. It has a total mileage of around 320,000 km. Over the past year, we've been facing an issue where it stalls, mainly when putting load on the engine. We're also getting error codes P0340 and P0335. Here's what we've done so far:

- Replaced the timing chain, piston rings, and related gaskets in 2020.Couple years went just fine.
- Replaced both crankshaft and camshaft position sensors, trying new and used ones, but the error still persists. We have like 4 or 5 of them now:)
- Swapped the throttle body with a similar one with lower mileage.
- Checked the engine oil pressure, and it meets the standard.
- Verified the timing marks on the camshaft and the crankshaft, and all teeth are intact.
- Installed a new battery.
- Checked the wiring from the engine control unit to the sensors with a continuity tester.
- Measured engine compression, and it's within normal range.

The engine runs smoothly and quietly, but it still stalls. Therefore, we suspect the issue might be with the engine control unit. I have no experience with replacing the engine control unit, so I would be grateful if someone could guide me through the process. Our engine control unit's number is A56 B39 E0J 7621.

We don't have any documentation for the T31 Exxies here in the 'States (although I do have FSM's for the late T30's), so I can only give you general advice. First, was the cam sensor you put in OE or aftermarket? If it was aftermarket, try OE. I'm not against aftermarket parts and there are plenty that will work fine on a Nissan, but crank and cam sensors are not among them. I can't tell you how much head-banging and heartache I've seen over the years from aftermarket Hall sensors.

Second, have you checked pin-fits on the wiring between the ECM and the sensor? If not, you need to. Without buying an expensive pin-fit gauge, you can use a piece of 0.65mm (0.025") music wire or a safety pin with about the same diameter (not larger than 0.026", 0.66mm). It should drag slightly when inserted into the female contacts. If there's no drag then the spring contact is shot, and that's causing your open circuit.

Wiring issues are a little harder to eliminate, but you can do that by removing the back-shell from the ECM connector, inserting back-probes into the connectors, and jumping the three wires from the ECM to the sensor one at a time. By giving the conductors a parallel path, if one of them has a partial break that's causing the issue, the code will remain gone when you drive it with the parallel jumper in place. If you find one of the conductors is compromised, you can just permanently route a parallel wire.

If the ECM does prove to be the problem, the Hitachi number on the outside only tells you it's the correct hardware, it doesn't tell you anything about the firmware program. That complicates finding a good used one, because you need to make sure it came from a model with the same year and options as yours, particularly transmission type and FWD/AWD. Because of the way the Nissan Consult works, on older vehicles, there's sometimes no good way to reflash a wrong program on a used unit which isn't right for the car. You'll also need to have the keys reprogrammed. The car may or may not start with the security lamp lit, but even if it does, you'll have exactly 7 starts before the ECM will lock out, so take it straight to a dealer or locksmith. Lastly, you'll need to clear out the self-learning (LTFT) and perform a Closed Throttle Position Learn (CTPL) and Idle Air Volume Learn (IAVL). Some ECM's in that era also stored the vehicle VIN, if yours does then it will need to be rewritten with your VIN number.

Thank you for your thoughtful response, VStar650CL.

Yes, we used original sensors and also checked the wiring as you described. Currently, we have purchased an oscilloscope, and we will be capturing waveforms.

Nevertheless, I still believe the issue lies with the ECU since we had this problem from the car purchase. Occasionally and very rare, when start driving on 1 gear, it could stall, and we had to wait for a certain time (5 seconds) before it would start again and it seems now it's just progressing.

You're most welcome, happy to help. One other thought, since the car is used and you don't know its history, have you checked the crank and cam reluctors for magnetic debris?