[BrianC302]

My wife was driving our Sorento today and she said she was at a light and went to accelerate and nothing would happen. She turned the car off and back on and it drove fine but the check engine light was on. I ran the code and it was a "P0638 Throttle Actuator Control Range/Performance B1".
.
It seems to be running fine now. I suppose it could just be the throttle body is dirty (car has 112,000 miles), the unit is bad, or a bad gasket or something.

Has anyone else run into this issue? Thanks

 

[ecanderson]

Haven't had it, but familiar with it. There are a couple of ways to get there.

Throttle position is compared to air flow, and if the two don't match up within a reasonable range for a period of 19 seconds (no idea where they came up with that number), the code pops.

The second requires understanding that there are two sensors involved with the drive by wire throttle. One is under your foot - accelerator position sensor (APS) - and the other is the throttle position sensor (TPS) which detects how far the motor has actually opened things up based upon your foot's request at the APS. If your requested throttle at the APS doesn't line up well with the results at the TPS, then you get this code, too.

Frankly, they should have split the two conditions. Would make things easier to troubleshoot. Not knowing which of the two conditions is setting the code opens up a lot more possible sources for it.

Since the problem resolved itself, it seems more likely that you're probably in the first case, and your assessment of a dirty MAP sensor or gasket issue (air leak somewhere between TPS and MAP) are certainly possible sources for the error.

 

[Billi]

What's the purpose of this though? I can sort of understand 1st condition. In the event that somehow not enough air is available, stepping on the gas will force the engine to burn too rich? That's perhaps a pollution/emission concern?

However, I don't get what the 2nd condition is for? If I depressed the pedal but not gas is going in the motor, why do I need sensors to tell me that? And I can't imagine if I don't depress the pedal, but motor somehow got gas and start revving... that'd be weird. Or hopefully sensor can detect the car is going crazy and stop it?

This added complexity just doesn't seem helpful to me. Am I missing something?

Anyway, I haven't run into this issue so far. Hope it can be resolved soon or won't happen again.

 

[ecanderson]

However, I don't get what the 2nd condition is for? If I depressed the pedal but not gas is going in the motor, why do I need sensors to tell me that?

Gas isn't what we're talking about here. That's the job of the fuel injectors.

There can be many reasons for lack of throttle response that pop entirely different codes.

This 2nd case tells you that pressing the accelerator seemingly hasn't produced the right response at the motor that actually controls the throttle valve which controls air coming into the engine, or at any rate that the sensor that is supposed to detect the actual motion isn't happy with what it sees. That (TPS) sensor used to be a VERY common failure for the previous generation, but has its own associated codes. In this 2nd case you may also have other accompanying codes that point even further to the source of the problem.

 

[Billi]

So I guess it's purely there to help techs diagnose problems.

So back to the 1st condition, the car should simply pop a code if that's the issue, right? It shouldn't cause the pedal to be unresponsive, right? All those sensors are just there to make sure everything is running accordingly..., if not, it'll throw a code. They won't actively intervene and do something to fix problems, right?

Anyway, whenever a problem that can be solved by restarting the whole system, kinda points to a computer glitch to me.

 

[ecanderson]

So I guess it's purely there to help techs diagnose problems.

So back to the 1st condition, the car should simply pop a code if that's the issue, right? It shouldn't cause the pedal to be unresponsive, right?

Anyway, whenever a problem that can be solved by restarting the whole system, kinda points to a computer glitch to me.

In the first case where there's a disconnect between estimated and actual air flow, yes, it's possible for the system to briefly see such a strange error (e.g., briefly think there is no or nearly no air flow into the engine) that the ECU has no reason to add fuel via the injectors, either. Pushing the pedal would throw a code, and the engine RPMs wouldn't increase in response to the pedal.

Restarting may or may not have been what solved the problem. The glitch may have been transitory, but from a real source (e.g., faulty MAPS output).

 

[leo42.2875]

A coked up (dirty) throttle body will restrict the air flow and require a larger throttle plate angle to satisfy the Pedal request to the ECU. The function is halted to ensure no inadvertent run-away.

Clean the throttle body and MAF, then reinitialize the ECU, start the engine , do not touch the go peddle, for a couple of minutes, then drive as normal, the ECU will now relearn its driving function, expect rough/low idle for a while.

 

[ecanderson]

Clean the throttle body and MAF ...

Not on this vehicle. This one uses a MAP. Different location, a bit further 'in' I guess you'd call it.

 

[leo42.2875]

The key is to allow the throttle plate to rest in factory position, not sitting up on a coked barrel..

 

[Billi]

Okay, you guys are saying lots of things flying over my head now…

just out of curiosity, has any of you experienced the same problem with your Sorento? Hope this depress the gas pedal and car won’t go problem isn’t common.

 

[leo42.2875]

If you dont understand, find someone to at the very least clean your throttle body, TB cleaner, a tooth brush and a clean rag..

How to Clean Throttle Body without Removing It – Rx Mechanic

What is a Throttle Body Service and Why is it Important - Autos.com

 

[BrianC302]

Thank you for all of the responses. I really appreciate it.

 

[Billi]

So is this issue resolved for you?

 

[DefMan]

I take it that the throttle bottle cleaning is the same as spraying CRC cleaner for carbon buildup? Like the thread we did here back in July? How to prevent carbon buildup using CRC intake cleaner

 

[leo42.2875]

I take it that the throttle bottle cleaning is the same as spraying CRC cleaner for carbon buildup? Like the thread we did here back in July? How to prevent carbon buildup using CRC intake cleaner

No, that is a different issue and different resolution..