Corsa C P0170 error code

gjs6385

Hi I’ve got the very irritating and vague P0170 error code and have already replaced both lambda/oxygen sensors and the brake servo vacuum pipe but it’s still remains and I’m getting a high revving at idle up to 1500rpm on some occasions.  Here is some live opcom data I recorded:

https://mega.nz/file/ri4CgbBb#2fwVSnPyzlS83Qt18GfT2wcWIp64YU-5_frZB-pwm78

I would be grateful for any thoughts as to what the issue might be.  I’ve wondered whether it could be the EGR valve sticking open possibly.

Goudy

This could be due to a long list of problems.

Air leaks and exhaust leaks are common issues that send the 02's lean.
Unmetered air entering the engine will obviously lean out combustion and exhaust gases escaping will effect the O2.

An EGR stuck open may have a similar effect, though you could try blanking off the exhaust feed to it as a simple check.

Also, there are problems that cause the ECU to think it's running richer or leaner than it is, like a bad MAF or a problem with another set of data that the ECU just can't adjust for, though thos last one will generally force the ECU into a extra rich/safe running mode.

It's a long time since I dealt with a Corsa C, but I have had several servo issues with a few that have caused unmetered air to enter the engine.
The hard plastic vacuum pipe can fracture, usually around the check valve on the servo (though it looks like you're replaced this) and the servo itself can rot out and leak as water gets in behind it.
You can do a simple brake pump test, run the engine a while, then hold the brake pedal down with just enough pressure to feel solid and turn off the engine, then start counting. If the pedal sinks immediately or within a few seconds, the servo is leaking.

You might have more luck on the Corsa C forum.

gjs6385

Goudy said:

This could be due to a long list of problems.

Air leaks and exhaust leaks are common issues that send the 02's lean.
Unmetered air entering the engine will obviously lean out combustion and exhaust gases escaping will effect the O2.

An EGR stuck open may have a similar effect, though you could try blanking off the exhaust feed to it as a simple check.

Also, there are problems that cause the ECU to think it's running richer or leaner than it is, like a bad MAF or a problem with another set of data that the ECU just can't adjust for, though thos last one will generally force the ECU into a extra rich/safe running mode.

It's a long time since I dealt with a Corsa C, but I have had several servo issues with a few that have caused inmetered air to enter the engine.
The hard plastic vacuum pipe can facture, usually around the check valve on the servo (though it looks like you're replaced this) and the servo itself can rot out and leak as water gets in behind it.
You can do a simple brake pump test, run the engine a while, then hold the brake pedal down with just enough pressure to feel solid and turn off the engine, then start counting. If the pedal sinks immediately or within a few seconds, the servo is leaking.

You might have more luck on the Corsa C forum.

Thanks I’ve posted on that forum too just looking for other opinions and your response is very helpful.

As you say I’ve replaced the brake servo vacuum pipe but I’ll try the brake pump test and I’ve noticed that when the revving happens if I press the brake a few times it makes it rev higher so maybe it is the servo that is leaking?