What are the Possible Causes of the Code P00C7?

• Vacuum Leak,
• Faulty Barometric Pressure (BARO) Sensor
• Barometric Pressure Sensor harness is open or shorted
• Barometric Pressure Sensor circuit poor electrical connection
• Faulty Manifold Absolute Pressure (MAP) Sensor
• Manifold Absolute Pressure Sensor harness is open or shorted
• Manifold Absolute Pressure Sensor circuit poor electrical connection
• Wiring connector not fully plugged into a sensor
• If it has a turbo, it also has a BARO sensor
• At idle, see if MAP reports normal KPA value

 

What are the Possible Causes of the Code P00C7?

• Vacuum Leak,
• Faulty Barometric Pressure (BARO) Sensor
• Barometric Pressure Sensor harness is open or shorted
• Barometric Pressure Sensor circuit poor electrical connection
• Faulty Manifold Absolute Pressure (MAP) Sensor
• Manifold Absolute Pressure Sensor harness is open or shorted
• Manifold Absolute Pressure Sensor circuit poor electrical connection
• Wiring connector not fully plugged into a sensor
• If it has a turbo, it also has a BARO sensor
• At idle, see if MAP reports normal KPA value

Much appreciated. I did check for a vaccum leak, everything seems connected and secure. The hose from the BoV to the intake was removed at the BoV to make getting to the O2 sensor a little easier, but that is back connected solid. Also, I've had a vacuum leak before, and it caused all sorts of idle and drivability issues. The car seems to be driving fine.

I found this while searching. Although it's for a Cruze, 3 sensors are checked to find the one that is more than 1.5psi out of range with the others (3:25)

He's using some specific software to monitor PSI here, does anyone know if HPT can do the same? Wondering if I can narrow down which sensor is having trouble if this is a sensor issue.

 

Not the time to watch 17 minutes of that video but

The Hptuners has the PIDs as I show (and check if having a turbo any sensor )
to scan and record to debug is a Vacuum or leak issue(s)

 

Not the time to watch 17 minutes of that video but

The Hptuners has the PIDs as I show (and check if having a turbo any sensor )
to scan and record to debug is a Vacuum or leak issue(s)

Thanks man and apologies for the long video. I did put the time stamp where he compares the values (3:25). I had a couple of these loaded, I added the Intake Manifold Abs Pressure and Manifold vacuum. Going to give this a go:

Some of ones I added in appear to be replicated by what was already there, so it looks like I was collecting 2 of the 4 you recommended already. This was at idle. If anyone thinks any of these values indicate a vacuum leak/sensor issue, I'd appreciate the advice.

 

Limited data as you just have a snapshot of 1 cycle, but the values look to be all within range
Though the problem maybe random, or happen when cold or maybe hot, or driving with and without boost

You need if you can clear the DTC and then with scanner recording make a custom PID group of
RPM, MAP boost map, Vacuum from idle to driving
You want VAC in that PID group since it is inverse of MAP and shows a problem easier when comparing

Then export recording to CSV/Txt for Excel and analyze IF the values related to MAP are the same or within the
range mentioned in that video to see if in face the issue is there or some wiring or sensor issue

 

Limited data as you just have a snapshot of 1 cycle, but the values look to be all within range
Though the problem maybe random, or happen when cold or maybe hot, or driving with and without boost

You need if you can clear the DTC and then with scanner recording make a custom PID group of
RPM, MAP boost map, Vacuum from idle to driving
You want VAC in that PID group since it is inverse of MAP and shows a problem easier when comparing

Then export recording to CSV/Txt for Excel and analyze IF the values related to MAP are the same or within the
range mentioned in that video to see if in face the issue is there or some wiring or sensor issue

Thank you. I'll give this a try.

 

Also,
when DTC trips, make sure you were scanner recording and then look at the freeze-frame with scanner to see exactly went was going on the moment DTC tripped

 

Also,
when DTC trips, make sure you were scanner recording and then look at the freeze-frame with scanner to see exactly went was going on the moment DTC tripped

It happens on startup. I can shut off the car, clear the DTC, and it comes back on restart.

I know this may be a question, but can you clear DTCs with the engine running? I've always done it with the ignition on only. If it's safe to clear them while the engine is running, I could run a scan as you describe.

 

You can clear DTCs anytime you want
That would be helpful to see that if the DTC only trips on hot or cold starts and if cleared after engine running how the engine functions

Still will be interesting if DTC cleared, scanner recording, quickly turn off
key on, engine off does the DTC trip without an engine start
and DTC cleared, key off, while scanner recording, startup, DTC trips, what does the freeze-frame show in these testcases ?

 

You can clear DTCs anytime you want
That would be helpful to see that if the DTC only trips on hot or cold starts and if cleared after engine running how the engine functions

Still will be interesting if DTC cleared, scanner recording, quickly turn off
key on, engine off does the DTC trip without an engine start
and DTC cleared, key off, while scanner recording, startup, DTC trips, what does the freeze-frame show in these testcases ?

Thanks, good to know I can clear at any point.

Interestingly enough, had an appt this morning, CEL was present on startup. Drove to appointment, car sat for about an hour and 45 mins, CEL was no longer present when I restarted. Oil temp as ~115 degrees on restart. Didn't come on during trip home. Will monitor and see if it comes back, and will try all the things you mentioned.

 

You didn't say what model year your ATS-V is but for MY17, DTC P00C7 is a problem in the system of sensors used to measure intake air pressure.

GM's specific fault description is: Intake Air Pressure Measurement System - Multiple Sensors Not Plausible, ie: there are one or more sensors that are giving the ECM readings that it believes are unlikely or impossible.

This fault code sets if the ECM detects an inconsistency between pressure sensors in the induction system in which a particular sensor cannot be identified as the failed sensor. The difference is greater than 10 kPa (1.5 PSI)

The sensors that make up the intake Air Pressure Measurement System are:
1) Barometric Pressure (BARO) 1 (Turbocharged Inlet Air Pressure–TCIAP)
2) Barometric Pressure (BARO) 2 (TCIAP 2)
3) Manifold Absolute Pressure (MAP) Sensor
4) Turbocharger Boost / Intake Air Temperature Sensor

If you have a scan tester that records freeze frames, set the tester up to save FFs and start the engine. As soon as the test for P00C7 fails, a freeze frame should be recorded.

If you using HPT's ECM Scanner, make sure you start scanning before you start the engine, then start. In the scan, you should find the sensor data that's causing P00C7 to fail. You can use ECM Scanner to read FFs using the procedure discussed here.

Being that you've had occasions of P00C7 setting on start-up, then some starts without it setting, this P00C7 might be intermittent.

As soon as the test fails, you will have an FF of what those sensors were doing when the test failed. DTC P00C7 is a "Type B" DTC so the ECM requests the MIL only after the second time it fails. If this is an intermittent problem and the DTC test has only failed once since the last clear codes, you may already have a FF available even though the MIL is not on.

The GM diagnosis and repair instructions for P00C7 are fairly long so, IMO your choices are two:
1) Buy a three-day subscription to GMSI for 22 bucks and use the diagnostic instructions in Engine Controls and Fuel - 3.6L LF4 LGX > Diagnostic Information and Procedures >DTC P00C7 as a guide to troubleshooting and repair.

2) Check all wires and connections related to the induction system and if you find nothing there that is suspect, start throwing parts at the problem.

Good luck and, if you find and repair a problem, please report back to this thread.

 

You didn't say what model year your ATS-V is but for MY17, DTC P00C7 is a problem in the system of sensors used to measure intake air pressure.

GM's specific fault description is: Intake Air Pressure Measurement System - Multiple Sensors Not Plausible, ie: there are one or more sensors that are giving the ECM readings that it believes are unlikely or impossible.

This fault code sets if the ECM detects an inconsistency between pressure sensors in the induction system in which a particular sensor cannot be identified as the failed sensor. The difference is greater than 10 kPa (1.5 PSI)

The sensors that make up the intake Air Pressure Measurement System are:
1) Barometric Pressure (BARO) 1 (Turbocharged Inlet Air Pressure–TCIAP)
2) Barometric Pressure (BARO) 2 (TCIAP 2)
3) Manifold Absolute Pressure (MAP) Sensor
4) Turbocharger Boost / Intake Air Temperature Sensor

If you have a scan tester that records freeze frames, set the tester up to save FFs and start the engine. As soon as the test for P00C7 fails, a freeze frame should be recorded.

If you using HPT's ECM Scanner, make sure you start scanning before you start the engine, then start. In the scan, you should find the sensor data that's causing P00C7 to fail. You can use ECM Scanner to read FFs using the procedure discussed here.

Being that you've had occasions of P00C7 setting on start-up, then some starts without it setting, this P00C7 might be intermittent.

As soon as the test fails, you will have an FF of what those sensors were doing when the test failed. DTC P00C7 is a "Type B" DTC so the ECM requests the MIL only after the second time it fails. If this is an intermittent problem and the DTC test has only failed once since the last clear codes, you may already have a FF available even though the MIL is not on.

The GM diagnosis and repair instructions for P00C7 are fairly long so, IMO your choices are two:
1) Buy a three-day subscription to GMSI for 22 bucks and use the diagnostic instructions in Engine Controls and Fuel - 3.6L LF4 LGX > Diagnostic Information and Procedures >DTC P00C7 as a guide to troubleshooting and repair.

2) Check all wires and connections related to the induction system and if you find nothing there that is suspect, start throwing parts at the problem.

Good luck and, if you find and repair a problem, please report back to this thread.

Thanks! Apologies, my car is a 2016. I'm scanning with HPT, but the DTC has cleared on it's own and hasn't come back. I'm set to grab the freeze frames as you detailed (thanks for the link!), and I'm scanning prior to starting the engine. Now I just need it to happen again.

In my reading, I found multiple articles about different platforms (Escalade, Tahoe, non-V ATS, Cruze) having "fantom" P00C7 DTCs that come and go. I hope I'm not headed down that path.

An added bonus of getting the car on a lift was finding that my driver side rear shock is leaking fluid, so I'll be back on a lift soon to replace it, which will give us some time to troubleshoot these induction system sensors also.

 

A lot of MR shocks get replaced unnecessarily. When you say it's leaking...is it dripping gray fluid?

 

Yeas, the body of the shock is pretty covered in fluid.. I can't tell the color to be honest, because it's mixed with road grime.

 

If it's dripping, it's leaking. If it has a film partially covering the shock body but there's no fluid leaking, the shock might be good.

 

Thanks Hib. The rear shocks were relatively inexpensive, so I'm just going to replace them when we put the lowering springs on.

As for P00C7, it cleared and hasn't come back. I've scanned every time I have driven the car, and nada. Go figure. Maybe the car was just getting used to the new O2 sensor lol. I'll keep scanning for a while, but it's getting laborious to constantly take my laptop out the car every time I need to go somewhere.

 

So after almost 2 weeks of taking the laptop to the car with me for every single outing with the car, and basically leaving the MPVI plugged into the OBDII port, the DTC hasn't come back. Go figure. Thanks to everyone for the suggestions and advice, I really appreciate it. You guys were more than helpful.

 

Damn if this thing didn't disappear for a few weeks, and then pop back up again yesterday. I cleared it out, started scanning, and restarted. Here is a FF capture, does this provide any clues to those who know?

DTC: P00C7 - Intake Air Pressure Measurement System - Multiple Sensor Correlation
Fuel System Status: 00 00
Calculated Engine Load: 0 %
Engine Coolant Temp: 86 °C
Short Term Fuel Trim Bank 1: 0 %
Long Term Fuel Trim Bank 1: 14.0625 %
Short Term Fuel Trim Bank 2: 0 %
Long Term Fuel Trim Bank 2: 14.84375 %
Fuel Pressure: 438.000456869517 kPa
Intake Manifold Absolute Pressure: 52 kPa
Engine RPM: 0 rpm
Vehicle Speed: 255 km/h
Timing Advance: 20 °
Intake Air Temp: 21 °C
Mass Airflow: 0 g/s
Throttle Position: 31.7647058823529 %
O2 Voltage B1S1: 77.5 mV
O2 Voltage B1S2: 1279.98046875 mV
O2 Voltage B2S1: 42.5 mV
O2 Voltage B2S2: 94.98046875 mV
Run Time Since Engine Start: 187 s
Fuel Rail Pressure: 4 MPa
Commanded EVAP Purge: 0 %
Fuel Level Input: 93.3333333333333 %
Warmups Since MIL Clear: 5
Distance Since MIL Clear: 218 km
EVAP System Vapor Pressure: 16337 kPa
Barometric Pressure: 100 kPa
Catalyst Temp B1S1: 494 °C
Catalyst Temp B2S1: 494 °C
Control Module Voltage: 0 V
Absolute Load: 0 %
Commanded EQ Ratio: 1
Relative Throttle Position: 21.9607843137255 %
Ambient Air Temp: 4 °C
Absolute Throttle Position B: 31.7647058823529 %
Accelerator Position D: 19.2156862745098 %
Accelerator Position E: 9.41176470588235 %
Commanded Throttle Actuator: 21.5686274509804 %
Fuel Type: 00
60: 05 08 00 00

Thanks!

 

Was this at idle ?

Long Term Fuel Trim Bank 1: 14.0625 % (Way Lean !)
Long Term Fuel Trim Bank 2: 14.84375 %
Ambient Air Temp: 4 °C (is that what the weather temp was ?)
O2 Voltage B1S1: 77.5 mV
O2 Voltage B1S2: 1279 mV
O2 Voltage B2S1: 42.5 mV
O2 Voltage B2S2: 94 mV
Intake Manifold Absolute Pressure: 52 kPa
Barometric Pressure: 100 kPa (not right )

Not make sense

Engine RPM: 0 rpm
Vehicle Speed: 255 km/h
Absolute Load: 0 %

What are the Possible Causes of the Code P00C7?

• Check for your vehicle is BARO and MAP same sensor, or 2 sensors, check wiring
• Faulty Barometric Pressure (BARO) Sensor
• Barometric Pressure Sensor harness is open or shorted
• Barometric Pressure Sensor circuit poor electrical connection
• Faulty Manifold Absolute Pressure (MAP) Sensor
• Manifold Absolute Pressure Sensor harness is open or shorted
• Manifold Absolute Pressure Sensor circuit poor electrical connection
• The Intake Air Pressure Measurement System consists of (2) sensors, the Barometric Pressure (BARO) Sensor, and the Manifold Absolute Pressure (MAP) Sensor.
• The Diagnostic Trouble Code (DTC) will be set when the ECM detects an inconsistency between pressure sensors in the induction system, in which a particular sensor cannot be identified as the failed sensor.
• The difference between them is greater than 10 kPa (1.5 PSI).

 

Was this at idle ?

Long Term Fuel Trim Bank 1: 14.0625 % (Way Lean !)
Long Term Fuel Trim Bank 2: 14.84375 %
Ambient Air Temp: 4 °C (is that what the weather temp was ?)
O2 Voltage B1S1: 77.5 mV
O2 Voltage B1S2: 1279 mV
O2 Voltage B2S1: 42.5 mV
O2 Voltage B2S2: 94 mV
Intake Manifold Absolute Pressure: 52 kPa
Barometric Pressure: 100 kPa (not right )

Not make sense

Engine RPM: 0 rpm
Vehicle Speed: 255 km/h
Absolute Load: 0 %

What are the Possible Causes of the Code P00C7?

• Check for your vehicle is BARO and MAP same sensor, or 2 sensors, check wiring
• Faulty Barometric Pressure (BARO) Sensor
• Barometric Pressure Sensor harness is open or shorted
• Barometric Pressure Sensor circuit poor electrical connection
• Faulty Manifold Absolute Pressure (MAP) Sensor
• Manifold Absolute Pressure Sensor harness is open or shorted
• Manifold Absolute Pressure Sensor circuit poor electrical connection
• The Intake Air Pressure Measurement System consists of (2) sensors, the Barometric Pressure (BARO) Sensor, and the Manifold Absolute Pressure (MAP) Sensor.
• The Diagnostic Trouble Code (DTC) will be set when the ECM detects an inconsistency between pressure sensors in the induction system, in which a particular sensor cannot be identified as the failed sensor.
• The difference between them is greater than 10 kPa (1.5 PSI).

Yes, at idle. And the temp was about 40 degrees, so I think 4C is correct.

 

52 kPa MAP and 100 kPa baro simultaneously are both totally possible provided the engine is running at moderate load and the car is being driven near sea level in elevation. However, the MAP at 52 kPa is not plausible for an engine off MAP to Baro correlation check which is when the ECM usually performs a MAP to Baro correlation test.

The MAP to Baro correlation test is usually performed by the ECM with the engine not running, as with the engine not running the MAP and Baro should both be reading atmospheric pressure and should read the same value within a few kPa. (The MAP and Baro should also agree at WOT with a naturally aspirated engine unless the air filters are extremely plugged, which will mean there is still some amount of vacuum in the intake because of the intake restriction, and the MAP will read lower than the Baro.)

In your freeze frame data it's showing 0% load, 0 RPM, and 0 g/s airflow rate, so it appears the engine was off when the correlation check was performed-- so the MAP and Baro should agree. The baro showing 100 kPa would be correct if you're near sea level and is probably reading OK, but the MAP showing 52 kPa with 0% load, 0 rpm, and 0 g/s airflow rate is totally incorrect, as with the engine off the MAP and Baro should agree within a few kPa. IMO that points to a MAP sensor issue or a wiring/connection issue between the MAP and ECM.

Your freeze frame data doesn't totally make sense though, as some of it indicates the engine was running and some indicates the engine wasn't running when the freeze frame was taken... but IMO it still points to a possible issue with the MAP sensor or MAP sensor wiring though. If it was me I'd pull the MAP sensor and start a trace on the MAP value while jiggling the connector at the MAP sensor and also slowing applying vacuum and pressure with a handheld vacuum/pressure pump. You might see the trace stick or spike indicating an issue. If the trace shows and issue while jigging the wiring and connector you probably have a pin fit or connector issue, if the trace shows an issue while slowing applying vacuum and pressure with the hand pump it's probably the MAP sensor (IIRC, it's actually a TMAP on these cars to also monitor temps in the intake manifold.)

 

Thanks, this is great info. When I get this DTC (it's disappeared again), it comes on when the ignition is on, before the engine starts. I started scanning before I started the engine, so my assumption was that the FF is from before the engine started. I'll take a closer look at the wiring to the MAP sensor. The MAP is for an LT4, and I noticed the wiring job uses some butte connectors. Maybe one of them has the potential to come loose.

 

So you're running a 3 bar LT4 TMAP sensor, and I'm guessing the MAP sensor scaling has been adjusted in your tune?

Did they chop and splice the factory harness or use an adapter harness for the LT4 TMAP? Nothing wrong with butt connectors provided they were crimped with the proper crimper, but it doesn't take much additional resistance in the circuit to substantially skew the reported values especially with a 3, 4, or 5 bar MAP sensors where a small voltage change yields substantially different kPa readings.

 

So you're running a 3 bar LT4 TMAP sensor, and I'm guessing the MAP sensor scaling has been adjusted in your tune?

Did they chop and splice the factory harness or use an adapter harness for the LT4 TMAP? Nothing wrong with butt connectors provided they were crimped with the proper crimper, but it doesn't make much additional resistance in the circuit to substantially skew the reported values especially with a 3, 4, or 5 bar MAP sensors where a small voltage change yields substantially different kPa readings.

Yep, the tune accounts for the LT4 TMAP sensor. I need to take a closer look at the wiring to confirm a splice or adapter harness. Thing is, this sensor has been in place for over a year, and this code has only recently appeared, and the only change has been that the motor was out of the car. So I'm wondering if something happened when everything was put back together, and something is just a little loose. The fact that the DTC is intermittent really has me wondering if something is just coming loose.