92 Volvo 940 doesn't slow down after releasing the gas
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92 Volvo 940 doesn't slow down after releasing the gas
Hello Dear Forum menbers,I’m seeking some diagnostic help for my Volvo 940. I am currently getting persistent Check Engine Light codes 122, 123, and 224 that return immediately after being cleared.
The Symptoms:
Are there any specific voltage or resistance tests I should perform before I throw more parts at it? Thanks in advance!"
The Symptoms:
- Cold Starts: Normal RPM, but requires pressing the gas pedal to fire up.
- Hot Starts: Idle jumps extremely high (2,000–3,000 RPM) once the engine is warm.
- Driving: The RPM hangs/stays high after releasing the gas pedal; it only drops after braking or waiting a long time only happened in gear 3 and 4
- IAC Test: When I unplug the Idle Air Control (IAC) valve, the RPM stay at 500rpm
Are there any specific voltage or resistance tests I should perform before I throw more parts at it? Thanks in advance!"
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Goldenblock here! Senior member...
The symptoms you described are a perfect candidate for a bad or mid adjusted throttle position sensor
Manually with car off twist your throttle pulley and listen for a faint clicking noise.
If no noise than look into the proper adjustment or replacement. Vdo for Regina
Blessings
The symptoms you described are a perfect candidate for a bad or mid adjusted throttle position sensor
Manually with car off twist your throttle pulley and listen for a faint clicking noise.
If no noise than look into the proper adjustment or replacement. Vdo for Regina
Blessings
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Repair Update: The Volvo is Running!
Happy holidays! I finally had some time to work on the Volvo today. After hearing a slight click when turning the pulley, I confirmed everything was fine mechanically.
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Repair Update: The Volvo is Running!
As I retraced my steps, I realized the Check Engine Light first appeared right after I installed a new coolant temperature sensor (CTS). I couldn’t clear Code 224 no matter what I tried. I decided to swap the new sensor out and reinstall the original OEM Bosch CTS. (I purchased a new sensor because the temperature gauge has been intermittently failing.)To reset the system, I disconnected the negative battery cable and jumped it to the positive wire to drain any remaining capacitance. The result? The engine fired right up with no lights and no codes!
I feel a bit silly because I already ordered a bunch of unnecessary parts, but I’m just happy it’s fixed. I also tested the IACV (Idle Air Control Valve) with a 12V source; it clicked and opened perfectly, so that's one less thing to worry about. Sometimes the urge to fix things quickly makes me skip the most important diagnostic steps.
Lessons Learned:
- Stick to OEM: Never use non-OEM replacements for critical sensors.
- Test, Don't Guess: Never assume a part is the problem without testing it first.
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From: Where freedom began ... and now goes to die
Thanks for the update! I always hate reading threads where the reader is left hanging and the OP vanishes into the ether. I appreciate the follow up!
I've been chasing kind of a similar problem with my '94 940 Bosch system with no cold start injector. The engine is extremely lean for some reason, so below 40° it becomes a crank, no start. Block the intake, or squirt brake clean in a vacuum port and it'll fire up, idle very low, and the fan comes on full bore. Already replaced the temp sensor for the ECU with no change at all. Once warmed up, it runs and starts perfectly every time, except for idling at 1,400 RPM. Very odd! After a couple years of this getting progressively worse each year, I've given up troubleshooting and have a couple bandaids. One is a coolant heater, and the other is a can of brake clean kept in the back. Either one gets it running no matter how cold it gets.
It's tough to pin down since when started warm or with the block heater, it just starts and idles normally. But when started ice cold on brake clean, the fan kicks on, then I notice changes in the brightness of the lights when I turn the running lights on, regardless of how high you rev the engine, indicating the computer is taking the field out of the alternator for some reason. Then after idling or running at a high RPM a minute or 2, the lights brighten back up, and the fan suddenly shuts down with a brief stumble, then everything is normal!
The bandaids are MUCH easier than trying to fix it right. Next summer I'll fix this permanently with a Weber carburetor.
I've been chasing kind of a similar problem with my '94 940 Bosch system with no cold start injector. The engine is extremely lean for some reason, so below 40° it becomes a crank, no start. Block the intake, or squirt brake clean in a vacuum port and it'll fire up, idle very low, and the fan comes on full bore. Already replaced the temp sensor for the ECU with no change at all. Once warmed up, it runs and starts perfectly every time, except for idling at 1,400 RPM. Very odd! After a couple years of this getting progressively worse each year, I've given up troubleshooting and have a couple bandaids. One is a coolant heater, and the other is a can of brake clean kept in the back. Either one gets it running no matter how cold it gets.
It's tough to pin down since when started warm or with the block heater, it just starts and idles normally. But when started ice cold on brake clean, the fan kicks on, then I notice changes in the brightness of the lights when I turn the running lights on, regardless of how high you rev the engine, indicating the computer is taking the field out of the alternator for some reason. Then after idling or running at a high RPM a minute or 2, the lights brighten back up, and the fan suddenly shuts down with a brief stumble, then everything is normal!
The bandaids are MUCH easier than trying to fix it right. Next summer I'll fix this permanently with a Weber carburetor.
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Goldenblock here! Senior member...
Last edited by renardanderson2; Feb 28, 2026 at 11:55 AM.
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Repair Update: The Volvo is Running!
As I retraced my steps, I realized the Check Engine Light first appeared right after I installed a new coolant temperature sensor (CTS). I couldn’t clear Code 224 no matter what I tried. I decided to swap the new sensor out and reinstall the original OEM Bosch CTS. (I purchased a new sensor because the temperature gauge has been intermittently failing.)To reset the system, I disconnected the negative battery cable and jumped it to the positive wire to drain any remaining capacitance. The result? The engine fired right up with no lights and no codes!
I feel a bit silly because I already ordered a bunch of unnecessary parts, but I’m just happy it’s fixed. I also tested the IACV (Idle Air Control Valve) with a 12V source; it clicked and opened perfectly, so that's one less thing to worry about. Sometimes the urge to fix things quickly makes me skip the most important diagnostic steps.
Lessons Learned:
- Stick to OEM: Never use non-OEM replacements for critical sensors.
- Test, Don't Guess: Never assume kitesurfing el gouna a part is the problem without testing it first.
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