Hi all,

I have recently bought a Ford focus 2019 (MK4). I have been having an issue with a spanner light that comes up on the dash and puts the car into limp mode, I’ve taken it back to the garage I bought it from many times but they can’t seem to figure out the issue, they changed the boost pipe and a valve somewhere on the turbo. 
eventually yesterday I took it to Ford for a diagnostic, they did lots of tests such as turbo boost tests, fuel tests, air intake tests and more and concluded there was nothing wrong with it?! 
 

I was and still am quite confused, why would a light come up and limp mode if everything in order? The light has come on probably close to 15 times since I bought the car in may. 
 

I just wanted to ask if anyone had any insight into the issue or maybe know of someone with the same? Everywhere I look I can’t find anything about it. 
 

the actual code said Turbocharger/Supercharger A Underboost Condition

 

When that happened lost power?

The performance was decreased a lot?

10 hours ago, hawksey45 said:

I was and still am quite confused, why would a light come up and limp mode if everything in order? The light has come on probably close to 15 times since I bought the car in may. 

the actual code said Turbocharger/Supercharger A Underboost Condition

 

There actually is a problem. The issue is that the problem may be intermittent and therefore may be hard to diagnose.

In your topic title you mention that there is an Overboost condition while the mentioned DTC description mentions and Underboost condition. Which is it and what are the exact DTC codes?

In both situations the actual turbo boost measured by the MAP sensor does not correspond with the value being expected by the PCM. There can be several causes varying from an air leak to a defective vacuum pump or turbocharger.
 

On 10/4/2025 at 8:39 AM, JW1982 said:

There actually is a problem. The issue is that the problem may be intermittent and therefore may be hard to diagnose.

In your topic title you mention that there is an Overboost condition while the mentioned DTC description mentions and Underboost condition. Which is it and what are the exact DTC codes?

In both situations the actual turbo boost measured by the MAP sensor does not correspond with the value being expected by the PCM. There can be several causes varying from an air leak to a defective vacuum pump or turbocharger.
 

Hi, so the code is Turbocharger/Supercharger A Underboost Condition

Ford has run various tests on the car and checked the boost on the turbo. I see you mention about a map sensor, do you think that could be faulty maybe? 
 

Someone else asked about power loss and yes, when the light comes on, power decreases massively as it puts the car into limp mode. 

On 10/4/2025 at 8:22 AM, Bol said:

When that happened lost power?

The performance was decreased a lot?

Yes , Yes

Could be many things.

Very possibly N75 turbo solenoid.