Hi im Have Volvo S40 2.0Diesel the computer show ECM-2683 Bypass valve signal too high.Whats part I need to replace?

First is all always write down the codes you have present, it helps in closing down on the problem. I am assuming you have a 95 Mazda Milleinia

1. Start and run the engine and monitor the oxygen sensor signals and see if this sensor has bad readings still. Check for an open or shorted wire between the sensor and the Engine Control Module (ECM) if the signal is dropping out.

2. Listen for an exhaust leak in the area of the oxygen sensor, the leak could allow oxygen in to the exhaust and skew the sensor readings.

3. Inspect the ECM and ECM connector for signs of something that has been spilled on the ECM. Is the engine idling too high or too low then check this:-
1. Unplug the idle air control valve and turn the air bypass screw in to see if it will idle down. If it will idle down, adjust the idle speed to around 500 RPM's and then plug the idle air control valve back in.

2. If it still idles high, remove the air boot from the throttle body, block the air bypass ports with duct tape, hook the air boot back on and start it. This should make it not idle at all or just barley idle. If it does, the problem is in the idle air control valve.

3. If blocking the air ports doesn't cause it to idle down, the throttle plate must be sticking open. Clean the throttle plate really good and back the throttle stop screw off and then see if it idles down.

4. Verify the coolant level is not low and that coolant is circulating through the idle air control valve. Tech Tips: This idle air control valve is two valves in one. It is a fast idle thermo valve on one side and a duty cycle idle air control valve on the other.

I’m happy to assist further over the phone at https://www.6ya.com/expert/uttamjeet_2f3adc18600f8ede

Code 122 is for a low signal coming from the TPS. Since you have replaced the sensor, the problem may be in the wiring harness. The signal would need to be checked.
Code 405 is also a low signal coming from the EGR valve. Same thing, you need to check the signal with a scanner or volt meter.
And when the computer is not getting an acceptable reading from the TPS it uses a known good signal to bypass the sensor which will cause the idle speed and shifting problems. The computer does not know when you open the throttle.

An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. ----------------------------------------------------------------------------------------
XPROG-M V5.0

Try replacing gas cap first before you spend any money on more on repairs

P1550 is code ECM-510F, vehicle speed signal. It could be a signal too high, too low or lost all together. A Volvo scanner would give you best results as to what it really is

HI. The code and its respective definition will be located below:

P0108 --- Manifold Absolute Pressure/Barometric Pressure Circuit High

Here are a few possible causes for the high signal transfer of the circuit:

• Leaking EGR valve
• Vacuum leaks
• Dirty fuel injectors
• Wrong fuel pressure
• Low engine compression
• Ignition miss
• Carbon deposits on the intake valves
• Valve problems

Check the engine for the above faults. If all the points above check out Ok; Replace the MAP sensor.

You may want to have someone else take a look at it. The Nissan P1800 trouble code is not a transmission control problem. It is described as follows:

Trouble diagnosis name: VIAS control solenoid valve circuit.
Component Description:
The VIAS control solenoid valve cuts the intake manifold vacuum signal for power valve control. It responds to ON/OFF signals from the ECM. When the solenoid is off, the vacuum signal from the intake manifold is cut. When the ECM sends an ON signal the coil pulls the plunger downward and feeds the vacuum signal to the power valve actuator.
DTC detecting condition:
•An excessively low or high voltage signal is sent to ECM through the valve.
Possible cause:
•Harness or connectors (The solenoid valve circuit is open or shorted.)
•VIAS control solenoid valve

Check your vacuum hoses to make sure they are in good shape and are securely attached Aslo check the wiring harness is ok and securely attached as well. If they are, you’ll probably need to replace your VIAS. It's right next to the throttle body.

Thanks for your interest, problem solved in local service workshop.
Regards,
Nenad Danicic

P0035 - Turbo Charger Bypass Valve Control Circuit High
Can't find P1027 anywhere.  Sorry!