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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #1
A while back my 2012 Range Rover Sport would run noticeably rough (exhaust was smoking more than usual, idled a little erratically, and the car just seemed louder than usual. Every so often during startup the Reduced Performance indicator would come on as well. Normal driving seemed to be fine but sometimes when the car would idle, these symptoms would present themselves.

My mom, who owned the truck at the time, took it to the dealer twice. The first time they were unable to replicate the problem. The second time the check engine light had come on and they could troubleshoot the issues, with an astronomical fee of course.

They fixed the problem and I will attach pictures of the paperwork so owners who experience symptoms like these in the future will have an idea of what fixed mine.

Hope this helps!

IMG_3600.JPG IMG_3601.JPG
 

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2013-2015 Range Rover Sport
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175 Posts
Interesting. I have the SC version of that problem, only with mine they replaced the wiring harness that goes to the TB. I still get the code when I accelerate really hard.
 

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2010-2012 Range Rover Sport
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1,986 Posts
Your mom must be using it for diving? Short in gas pedal and throttle body to snorkel?
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #4
Uh oh, I am starting to get this again. This time on startup when the reduced performance came on and the car was running crazy rough, I plugged in my OBD2 and read two pending codes:

P2135 and P2105.

p2135- Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation
P2105- Throttle Actuator Control System (TAC) - Forced Engine Shutdown

Any insight into this guys?
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #5
The other day I did a kickdown on the throttle then all of a sudden the car cut power with a Reduced Performance message. It started running pretty rough and had no power. I pulled over, restarted the car and it was fine but the check engine light was now on.

Pulled the codes and it said:

PO336 which is the Crankshaft Position Sensor code.

Is something shorting these all out or something?

After driving a few days the CEL disappeared out of nowhere but the code is still stored.

Please help!
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #6
I think something is shorting out the fusebox in the engine bay. Possible thoughts are maybe the windshield drainage or maybe the sprayers for the windshield washer fluid. Will investigate more tomorrow.
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #7
No signs of water near the fusebox was found. Still stumped. What could be shorting these out? The actual components aren't bad, it's just that sometimes they get shorted which then trips the CEL or has the reduced performance come on.

A mechanic passing by as I was looking at my car at 4am suggested a bad ground being the culprit.
 

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2010-2012 Range Rover Sport
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797 Posts
I had the rough idle issue once and basically cleaned the throttle body sensor, MAF sensor and the air filters. It solved the problem so perhaps just a little preventative upkeep will do the trick. :)
 

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2010-2012 Range Rover Sport
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797 Posts
No signs of water near the fusebox was found. Still stumped. What could be shorting these out? The actual components aren't bad, it's just that sometimes they get shorted which then trips the CEL or has the reduced performance come on.

A mechanic passing by as I was looking at my car at 4am suggested a bad ground being the culprit.
Hey just read this and definitely could be a bad ground. I had similar grounding issues a while back. They replaced almost everything and finally it was a ground that was the problem. Since it was replaced the issue hasn’t come back.
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #10
Hey, do you remember which grounding was bad? Bad grounds can be a pain to chase around :/
 

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2013-2015 Range Rover Sport
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Discussion Starter #12

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #13
Probably have to remove the skid plate in front...will attempt that sometime
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #15
Started up my car today and the idle was kinda erratic and car was running like crap. On the screen, another "Reduced Performance" message. Pulled the codes, had two stored codes and one pending one.

Stored:
P2105-Throttle Actuator Control System - Forced Engine Shutdown
P2135-Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation

Pending:
U0402-Invalid Data Received From TCM

Turned off the car. Started it right back up- Same thing and engine light was on. Waited like two minutes then restarted it. Car restarted and idle was fine, performance was just fine and the engine light is still on.
 

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2013-2015 Range Rover Sport
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51 Posts
Discussion Starter #16
Will be checking that ground strap as soon as I get some time. Hoping it's just that.
 

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2006-2009 Range Rover Sport
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13 Posts
you have a dirty MASS AIR FLOW sensor. you can remove it and clean it!! very simple. youtube it!
 

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2002-2005 Range Rover Sport
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13 Posts
Hello everyone,
in fact I had this problem of engine performance solved myself, when I just bought my range rover. because the guy who sold it to me deceived me, he did not want to tell me about this problem of engine performance reduced.

so when it had happened to me while I was driving, I used my OBDII, TOOL and immediately I found that the auxiliary electrical coolant pump is not working properly, this pump is responsible to cool down the compressed air from the supercharger to below 100C, . in fact this failure is from the original manufacture because they have issued a technical bulletin for this matter. workers from Discovery production line was borrowed to help the people of range rover sport , but the electrical wiring connections have not got the same code color like in discovery, there fore , workers connect the auxiliary coolant pump wrongly which cause the impeller of the bump to turn reversely , and zero cooling efficiency occurs at high temperature of the supercharger.

in order to fix the Engine performance reduced fault you need to do the following:
1- buy a new auxiliary coolant pump.
2- cut the ( + , - ) electrical wires and connect them in reverse,
3- enjoy you range rover driving.


hope that this will help you all, :dance:
 
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