Engine managment light comes on and goes into limp mode , the fault codes are showing part c throttle body fault. have changed the throttle body twice and reset the codes even been into jaguar garage for latest updates on engine and gearbox, drives superb for a while then same again red light comes on back into limp mode ....arghhh

Links below to descriptions and checklists...

https://www.obd-codes.com/p2101

https://www.obd-codes.com/p0967

https://www.google.com/search?rlz=1C1CAFB_enGB673GB676&sxsrf=ACYBGNRiWHtSSWoYzpm1heKZQVUATlDLZQ%3A1573524319449&ei=XxPKXYKDG8usgQabxqfQBQ&q=P1780&oq=P1780&gs_l=psy-ab.12..35i39j0l9.103231.105789..129341...0.2..1.940.4684.5-2j4......0....1..gws-wiz.......0i71.DAC5tl1QsH0&ved=0ahUKEwjCruzwyuPlAhVLVsAKHRvjCVoQ4dUDCAs

have the fault codes read first

Please just google this, GM fault codes P2138, P2123

Because you mentioned tick over I am assuming this tends to happen as you change the position of the throttle which if electronic is a common cause of engine management light and limp mode.if you keep the throttle still whilst driving for any length of time ...you may again experience limp mode the minute you either slow or accelerate as the contacts in an electronic unit are intermittent.my cure is to switch off the engine and pump the throttle pedal hard all the way to the floor and releases several times .this seems to make the contacts connect more efficiently.if this is the culprit it may be worth replacing the throttle module.lastly any limp mode is always recorded on the ecu as an error code.if you want to get answers fast take it to a garage and have them OBD the car to confirm what's really going on.

Most of the time with the 5.3L in the GM vehicles it is a problem with the Throttle body for P1235 code. Usually you can pull the air intake off the throttle body, take a rag with some break cleaner and open the plate. Clean the inside of plate and throttle body. I will probably be Black Gunk build up that comes off. Just clean it really well. The sensor between the pedal and the throttle body have match signals. If one is off then it goes into reduced power mode. So this can be caused by this residue build up. It usually will fix your issue. It can come back but it will get you back on the road and help take you out of limp mode or reduced power mode.

Check n recalibrate the throttle body at the dealer with Tech2, possble electric throttle body failure causing ECM goes into the limp mode.

cam sensor fault. would need to change this sits in the top of the cam. also there is a crank sensor the work together to see what the engine is doing best to change both at same time. when fail engine goes into limp mode.and turns of ecu control. just basic setting limuets to under 4000 revs

You have four fault code there...

Code 11
Description: Engine not cranked since last reset or no ignition reference signal detected during cranking
Power loss light: Off
Limp-in mode: None

Possible Causes:
Engine hasn't been cranked since last reset - Power was removed from the logic module (disconnected or dead battery, etc.) and the logic module has no memory of seeing a signal from the ignition reference sensor. Crank the engine and check for the code again. If the logic module saw a signal, the code will be cleared. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working.

Bad connection or wiring - Check the wiring and connections between the hall effect sensor (located underneath the distributer cap) and the logic module. Check the continuity of the two 3 conductor cables coming out of the sensor--these are prone to fatiguing and breaking inside the insulation where they exit the sensor if the cables are not properly tied down. You may be able to resolder them. Clean and regrease any corroded connectors with dielectric grease and repair any shorts. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working (see above).

Hall effect sensor failure- Check the ignition reference sensor and fuel injector sync sensor cables. They are the two, flat 3 conductor cables coming out of the sensor at the base of the distributer cap. These often fatigue where they exit from the sensor. Upon replacing the sensor, make sure the cables are clipped or tied to the distributor cap shroud (or elsewhere) so they do not swing around. This code will not show up if the sensor simply fails. The logic module must be reset and the engine cranked to see if the sensor is working (see above).


Code 23
Notes: For throttle body injected (N/A) models only

Description: Throttle body temperature sensor signal out of range
Power loss light: On
Limp-in mode: Throttle body temperature of 70^F is assumed

Possible Causes
Throttle body temperature sensor failure - The sensor should measure 9,120 ohms to 10,880 ohms at 77^F. This sensor is located on the side of the throttle body, below the throttle plate.

Bad connection or wiring - Check the wiring and connections between the sensor and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease.

Diagnostic Method
Trigger Parameters
- Sensor output less than 0.06V or greater than 4.98V
Results If Component Fails
Fault code 23 is stored, the power loss light is turned on, and the logic module will enter limp-in mode, assuming a throttle body temperature of 70^F.

Code 32
Description: Logic module did not see a change in air/fuel ratio when EGR circuit was activated
Power loss light: Off
Limp-in mode: None

Possible Causes
EGR valve stuck open or closed - If the vehicle fails emmisions, then the valve may be shut. If the enigne runs poorly at low rpm or at idle, the valve may be stuck open. It may be the valve or the transducer valve. Test the transducer valve vacuum output. At idle, the transducer valve vacuum should be mostly bled, and there should be very little, if any vacuum at the output. When the engine is revved, the vacuum should increase. If the transducer is functioning properly, replace the EGR valve.

Bad EGR solenoid or Canister purge/EGR solenoid - The solenoid is located in the right, front fender next to one to three other solenoids. See the Understanding Solenoids page for information about how to test and repair solenoids.

Bad connection or wiring - Check the wiring and connections between the solenoid and the logic module (or SMEC). Clean and regrease any corroded connectors with dielectric grease and repair any shorts.

Diagnostic Method
Trigger Parameters
- The EGR solenoid was deactivated, but the oxygen sensor reading did not change
Results If Component Fails
Fault code 32 is stored.

Code 55
Description: End of message
Power loss light: Off
Limp-in mode: None

Possible Causes
No further fault codes are stored. If this is the only code received, then there are no codes stored in memory. This code will always be given, even if nothing is wrong. If you do not get this code, then you may not be retreiving the codes properly, or the power loss light may be burnt out. The light should come on for 1 second when the ignition is initally turned on as a bulb test.

Diagnostic Method
Trigger Parameters
- No further codes in memory


Hope this helps (remember to rate this answer).

CODE PO120 - TP SENSOR 1 SIGNAL RANGE PERFORMANCE. CODE P1516 - TAC MODULE THROTTLE ACTUATOR POSITION PERFORMANCE. CODE P2135 - THROTTLE POSITION SENSOR 1 - 2 CORRELATION ERROR. THIS IS A DEALERSHIP FIX YOU HAVE PROBLEMS OR FAULTS IN THE THROTTLE POSITION SENSOR.

Sounds like car is in limp home mode which needs reseting ,which may indicate you need a new Di Rail, or throttle body. Is engine management light on all the time if so Needs reseting. Hope this helps.