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Weird Mix of Engine Codes

OhOneSilver
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OhOneSilver Enthusiast

OhOneSilver

Posted
Posted

All three of these popped at once which seems odd to me.

P0446: Evap Emission System Vent Control Circuit

C0292: Lost Communication With Engine Control System

C0298: Powertrain Control Malfunction

 

I'm just getting the static Service Engine light, no other lights or screen messages while starting or driving.

 

Is this a wiring issue of some kind?

codes.jpeg

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
13 hours ago, OhOneSilver said:

All three of these popped at once which seems odd to me.

P0446: Evap Emission System Vent Control Circuit

C0292: Lost Communication With Engine Control System

C0298: Powertrain Control Malfunction

 

I'm just getting the static Service Engine light, no other lights or screen messages while starting or driving.

 

Is this a wiring issue of some kind?

codes.jpeg

 

 

 

You've got two issues going on.  Well, three technically.  

 

#1.  You didn't say what YEAR, MAKE and MODEL vehicle you've got.  Important detail.  

 

#2.  You've got a bad EVAP vent valve (most likely).  Very common on these trucks.

 

#3.  Your PCM isn't talking to the EBCM.  Could be a bad EBCM, bad PCM or a wiring issue and would need diagnosing for sure.  

Edited by newdude
OhOneSilver Enthusiast

OhOneSilver

Posted
  • Author
Posted
7 hours ago, newdude said:

CM isn't talking to the EBCM.  Could be a bad

1. Oh, right, 2001 Chevy Silverado

 

2. From what I've been told otherwise it could also be the gas tank pressure sensor, but I'm curious why that and the other codes would pop simultaneously. That seems strange to me.

 

3. This is why I'm suspecting it's maybe a wiring issue. If the harness near the rear left wheel has some kind of issue perhaps it would trigger both of these?

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
42 minutes ago, OhOneSilver said:

1. Oh, right, 2001 Chevy Silverado

 

2. From what I've been told otherwise it could also be the gas tank pressure sensor, but I'm curious why that and the other codes would pop simultaneously. That seems strange to me.

 

3. This is why I'm suspecting it's maybe a wiring issue. If the harness near the rear left wheel has some kind of issue perhaps it would trigger both of these?

 

1 - Being you are setting C0292 and C0298, are you 2wd with traction control?

 

2 - P0446 is vent control circuit so the vent solenoid valve has an electrical fault (or wiring to it).  99.9% of the time its just a bad vent valve.  If it was a pressure related code or another EVAP code, sure you could point to a bad pressure sesnor.

 

3 - Depends on what other circuits are there.  2001, the chassis harness that far back will have fuel and EVAP system wiring and circuits to the rear lighting.  If there were major issues in that harness so lots of corroded or broken wires, I'd think you'd have no working fuel pump, no or partial rear lighting, etc. 

 

2001 the ABS is 4 wheel ABS but its not 4 channel so all 4 wheels don't have their own sensors.  Its a 3 channel system so the front wheels each have a sensor, and then the rear is monitored via output speed or rear wheel speed sensor in the transmission (2WD) or transfer case (4WD).  And you don't have wheel speed sensor codes.   

 

 

 

Edited by newdude
OhOneSilver Enthusiast

OhOneSilver

Posted
  • Author
Posted
21 hours ago, newdude said:

 

1 - Being you are setting C0292 and C0298, are you 2wd with traction control?

 

2 - P0446 is vent control circuit so the vent solenoid valve has an electrical fault (or wiring to it).  99.9% of the time its just a bad vent valve.  If it was a pressure related code or another EVAP code, sure you could point to a bad pressure sesnor.

 

3 - Depends on what other circuits are there.  2001, the chassis harness that far back will have fuel and EVAP system wiring and circuits to the rear lighting.  If there were major issues in that harness so lots of corroded or broken wires, I'd think you'd have no working fuel pump, no or partial rear lighting, etc. 

 

2001 the ABS is 4 wheel ABS but its not 4 channel so all 4 wheels don't have their own sensors.  Its a 3 channel system so the front wheels each have a sensor, and then the rear is monitored via output speed or rear wheel speed sensor in the transmission (2WD) or transfer case (4WD).  And you don't have wheel speed sensor codes.   

 

 

 

1. Yes that's correct.

 

2. ok thanks

 

3. Interesting. So this implies it's the sensor in the transmission?

newdude Senior Enthusiast

newdude

Posted
Posted (edited)
20 hours ago, OhOneSilver said:

1. Yes that's correct.

 

2. ok thanks

 

3. Interesting. So this implies it's the sensor in the transmission?

 

 

Rear wheel speed sensor would be mounted externally near the tailshaft area of the transmission.  

Edited by newdude
  • 1 month later...
OhOneSilver Enthusiast

OhOneSilver

Posted
  • Author
Posted
On 11/11/2023 at 9:13 AM, newdude said:

 

 

Rear wheel speed sensor would be mounted externally near the tailshaft area of the transmission.  

Thanks for all the help.

 

I ended up replacing the vent solenoid valve and all codes went away after a week of driving

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