Hyundai Repair Questions? Ask a Mechanic for Answers ASAP
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When an engine goes into limp mode, it means that codes are stored within the engine control unit.
Did you check for fault codes? and if yes, what fault codes are you getting.
As these codes should provide us with direction. We will know which parts, systems or wiring we need to check. And we will proceed accordingly
If no codes are thrown, then it should not be limp mode.
Maybe it's just the dpf trying to regen.
When the problem happens, do you try taking the vehicle on a highway, and go on for arouund 20 minutes with the rpm higher than 2000, as this should complete the DPF regen procedure.
That actually is a good thing, one less system to worry about.
So, again, if there are no fault codes, then this would not be limp mode.
Can you please explain in detail what happens when the vehicle doesn't behave normally?
And did you check other modules for faults? (other than the engine module)?
Could you check it with a scantool when it does the problem, before turning the key off?
As there should be a fault code, or many. They maybe listed as pending fault codes.
Well, that code will cause a limp mode. It will cause the symptoms you described.
Since you have already replaced the sensor, i would suggest checking the wiring to that sensor.
You can check with ignition on:
terminal one on the pressure sensor to ground, you should get 4.5 to 5.5 volts
On terminal 2 (signal wire) to ground you should get around 0.5 V with ignition on. around 1 to 1.5 v at idle, and around 2.5 to 4.5 volts at full load.
That will confirm, the sensor is working correctly, so check the wiring for any problems.
One way to do that, is to have you live data on the scan tool, and wiggle the wiring harness, and look for changes in pressure reading.
As the problem is intermittent, did you check when the problem was current?
In this case, i would check the circuit between the tank and the high pressure pump. Since we have no apparent problems on the high side, the low side would still cause problems under high demand.