Engine power reduced - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Boosted10ss · 01-22-2018, 02:55 PM

Help out guys I been searching a can not find nothing. I changed TB, TB pigtail connection, accelerating pedal "3 times from autozone ", map and maf sensors. And still getting the reduce engine power light and code p2138. Their is times I reset the code and it works all day and sometimes it comes back on in 5 minutes or less. Any help would be appreciated. It's a 2010 camaro SS ls3

danvillekidd · 01-22-2018, 03:22 PM

At this point, i would check the harness for damage and recessed pins in the connectors.

Russell James · 01-22-2018, 03:38 PM

That code is the ECM is not seeing matching accelerator position sensor readings from the 2 APS sensors on the pedal. So it doesn't know which one to trust, so puts you in limp mode.

It's not a throttle body problem. Something is screwy between the 2 pedal sensors and the ECM.

On a scanner, key on... view APS 1 and APS 2. As you slowly move the throttle, the value on the two sensors should match and range from .46 to 4.75V.

If you are not seeing matching readings for both throttle sensors... there is where you start chasing the problem down.

Make sure both sensors are getting their 5V reference signal from the ECM.

The 5 volt reference is:

For APS #1 it is terminal F
For APS #2 it is terminal C

Key on, you need to see about 5V at those terminals. Disconnect the pedal connection, key on DVOM check what the V is at those two terminals.

Also take a real close look at the connector ends and look for anything pushed back or expanded. I like to take a high res phone pic and blow it up to make it easier to see. Being intermittent, sounds like a terminal has opened up or pushed back.

jonesaustin71.aj · 01-22-2018, 03:50 PM

Subbed to this one. I am in the exact same boat. Replaced throttle body 3 times/ pedal assembly twice, t.b. pigtail,maf sensor, fuse box.
The last thing I did was replace the battery and really cleaned the terminal connectors. I'm not convinced that was the issue but I am going on 2 months issue free.

2011 2SS A6

Boosted10ss · 01-22-2018, 06:48 PM

I'm going to check the 5 volt reference for aps 1 and 2 ...And I also thought of the battery since I currently have the red top optima been wanting to change it to the stock battery for my car

ATCK45 · 01-23-2018, 10:28 AM

Be sure to check the inline connectors for an issue. I believe there was a service bulletin warning of water intrusion in a bunch of different vehicles. X104 is by the brake booster and X102 is by the fuse block near the ECM (40way). APP1 and APP2 run through these connectors.

Russell James · 01-23-2018, 10:38 AM

I'd start with watching APS 1 and 2 on a scan tool. If you see one dropping out, then you will know which circuit to chase down. Along with closely looking at the connector ends at the pedal connection to make sure there are no issues there, and 5V at each of the reference circuits with key on.

As you are taking connections apart, along with physically looking for a pushed back pin or opened up female terminal... put a little dielectric grease in the female side of the connection. Do that to one connector at a time. And if the problem improves right after disconnecting/reconnecting with dielectric grease...you found the connection with the issue. ... and if that pedal has been disconnected multiple times, may need to get into that female side with a pick and try to tighten them up a hair. A lot of those connectors aren't really intended for multiple reconnects. After a few times, they loosen up.

samman11 · 01-23-2018, 10:39 AM

Maybe you should take it to an authorized service center for Camaros. Just a thought to help you from pulling your hair out.

01-23-2018, 10:28 AM	#6
ATCK45 Drives: 2012 45th Anniversary Convertible Join Date: Jul 2016 Location: Michigan Posts: 18	Check water intrusion I/P to Body harness Be sure to check the inline connectors for an issue. I believe there was a service bulletin warning of water intrusion in a bunch of different vehicles. X104 is by the brake booster and X102 is by the fuse block near the ECM (40way). APP1 and APP2 run through these connectors.

01-22-2018, 02:55 PM	#1
Boosted10ss Drives: 2010 Orange camaro ss turbo Join Date: Jan 2018 Location: Plainview TX. Posts: 2	Engine power reduced Help out guys I been searching a can not find nothing. I changed TB, TB pigtail connection, accelerating pedal "3 times from autozone ", map and maf sensors. And still getting the reduce engine power light and code p2138. Their is times I reset the code and it works all day and sometimes it comes back on in 5 minutes or less. Any help would be appreciated. It's a 2010 camaro SS ls3

01-22-2018, 03:22 PM	#2
danvillekidd 2013 ZL1 Drives: 2013 ZL1 m6 Join Date: Oct 2010 Location: Avondale AZ & Indy will always be home Posts: 870 View My Garage	At this point, i would check the harness for damage and recessed pins in the connectors.

01-22-2018, 03:38 PM	#3
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	That code is the ECM is not seeing matching accelerator position sensor readings from the 2 APS sensors on the pedal. So it doesn't know which one to trust, so puts you in limp mode. It's not a throttle body problem. Something is screwy between the 2 pedal sensors and the ECM. On a scanner, key on... view APS 1 and APS 2. As you slowly move the throttle, the value on the two sensors should match and range from .46 to 4.75V. If you are not seeing matching readings for both throttle sensors... there is where you start chasing the problem down. Make sure both sensors are getting their 5V reference signal from the ECM. The 5 volt reference is: For APS #1 it is terminal F For APS #2 it is terminal C Key on, you need to see about 5V at those terminals. Disconnect the pedal connection, key on DVOM check what the V is at those two terminals. Also take a real close look at the connector ends and look for anything pushed back or expanded. I like to take a high res phone pic and blow it up to make it easier to see. Being intermittent, sounds like a terminal has opened up or pushed back.

01-22-2018, 03:50 PM	#4
jonesaustin71.aj Drives: 2011 Black 2SS 6A Join Date: May 2017 Location: Mansfield, Texas Posts: 45	Subbed to this one. I am in the exact same boat. Replaced throttle body 3 times/ pedal assembly twice, t.b. pigtail,maf sensor, fuse box. The last thing I did was replace the battery and really cleaned the terminal connectors. I'm not convinced that was the issue but I am going on 2 months issue free. 2011 2SS A6

01-22-2018, 06:48 PM	#5
Boosted10ss Drives: 2010 Orange camaro ss turbo Join Date: Jan 2018 Location: Plainview TX. Posts: 2	I'm going to check the 5 volt reference for aps 1 and 2 ...And I also thought of the battery since I currently have the red top optima been wanting to change it to the stock battery for my car

01-23-2018, 10:38 AM	#7
Russell James Drives: '15 SS 1LE, '69 Z28 drag car Join Date: Dec 2009 Location: Mich Posts: 4,482	I'd start with watching APS 1 and 2 on a scan tool. If you see one dropping out, then you will know which circuit to chase down. Along with closely looking at the connector ends at the pedal connection to make sure there are no issues there, and 5V at each of the reference circuits with key on. As you are taking connections apart, along with physically looking for a pushed back pin or opened up female terminal... put a little dielectric grease in the female side of the connection. Do that to one connector at a time. And if the problem improves right after disconnecting/reconnecting with dielectric grease...you found the connection with the issue. ... and if that pedal has been disconnected multiple times, may need to get into that female side with a pick and try to tighten them up a hair. A lot of those connectors aren't really intended for multiple reconnects. After a few times, they loosen up.

01-23-2018, 10:39 AM	#8
samman11 Drives: 2011 Camaro SS Convertible Join Date: Nov 2015 Location: Rochester, NY Posts: 671	Maybe you should take it to an authorized service center for Camaros. Just a thought to help you from pulling your hair out.