It helps with root cause to find the issue. See here in the Volvo 700-900 series FAQ and non-Turbo 700-900 used the same Bosch engine control system for the LH-Jetronic 2.4 / 3.1 injection and emissions, and EZK116 ignition and emissions.

Probe end in socket 2 for fuel and 6 for ignition. COPY and PASTE URN into new browser tab address field.

https://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm

See tables 1 and 2.

Take a read here. Have a service manual? Auto or manual?

I'll guess US market 1989 Volvo 245? If US, what state. CA, NY, Germany all inspect the pollution devices.

As VolVolina says as all air filter boxes with the air temperature thermostat that controls preheated air drawn through an accordion style hose connected between the exhaust manifold heat shield and the bottom of the air filter box.

You replace the thermostat or, with slightly reduced mileage and raised emissions in cold weather, convert to a cold air intake by removing the flappy valve assembly and removing the solver accordion hose the intake uses to draw preheated air. Borg Warner Wahler makes this as PN 70411 yet another is the OEM make of it yet forget.

Also, on 34-year old 1989 Volvo 245 are the vacuum lines from the air filter box out to the air intake port manifold may be failing as these embrittle over age, heat. The large accordion style hose can chafe in the inner fender in front of the brake master cylinder. Also, the PCV piping can be brittle and leaking vacuum. Is your engine clean of covered in oil?

Nice and clean and clear DOT 4 brake fluid?

You have prior owner service records?

Sorry to go on so.

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