2008 Pathfinder 4ltr Limp mode fault

[Jjparker11]

Hi Guys.

Might be similar to other faults I have read about on here but ill put it out there.

2008 petrol 4ltr Ti model R51Auto
200,000 Km

Some days its fine other days it enters limp mode without warning. No warning lights appear on dash until you drive for about 10km then the VDC off light comes on and the traction light also. They stay solid on until you shut it down. The motor sounds fine, exhaust has a tiny rattle when under load, could it be the Cat?

After reading other issues I'm a bit lost where to start, what is the most common issue to cause this? And i'll start there.

Thanks!

[Jjparker11]

A bit to add.
Cruise control also stops . Wont rev past 2500rpm and if you give it some throttle it won't kick down .
Only mods are a snorkel and mud tyres fitted to original wheels

[04pathse]

check engine light ?

[Jjparker11]

No check engine light has come on .

[Slumpert]

I would start with a ABS/Transmission capable code reader. Your not dealing with a engine issue, the ECU is going into limp mode because it being told something in the drivetrain is not working right.
Wheel sensor, steering angle sensor, transmission issue can all cause the car to drop into limp mode.

[Jjparker11]

So after a scan with the correct tool .
Code came up that was for a brake pedal sensor , replaced with genuine new one and still going into limp mode .
After trying to simulate the fault it turned out the previous owner put cheap led tail/stop light bulbs in and it was messing with the sensor .
Replaced bulbs with standard and fault gone .
Failed to realize sooner that it was only going into limp when the park lights or headlight where on .