My volvo 940 1993 keeps flashing the emission light when I restart warm car after a short trip - slow to start, need to give it some gas & rev

The check engine light comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. To determine the cause, the vehicle will need to be taken to AutoZone or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area.

A flashing check engine light is an indication of a severe misfire or problem that is likely to harm your engine. Immediate diagnosis and service is needed.

Some specific causes for the light to be on are:

Gas cap left off, not tightened, not installed correctly, or needs to be replaced

02 sensor

Engine misfire - error might clear itself after 3 complete warm-up cycles; not restarts, but warm-ups

At start up for a bulb check - Should not stay on

Problem in the emission system, including clogged exhaust or the catalytic converter not functioning properly

Dirty/clogged air filter

Dirty MAF sensor

There are pages and pages of items that can cause a check engine light to come on. Having it checked with a scan tool will narrow down the problem area.

The check engine light comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. To determine the cause, the vehicle will need to be taken to AutoZone or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area.

A flashing check engine light is an indication of a severe misfire or problem that is likely to harm your engine. Immediate diagnosis and service is needed.

Some specific causes for the light to be on are:

Gas cap left off, not tightened, not installed correctly, or needs to be replaced

02 sensor

Engine misfire - error might clear itself after 3 complete warm-up cycles; not restarts, but warm-ups

At start up for a bulb check - Should not stay on

Problem in the emission system, including clogged exhaust or the catalytic converter not functioning properly

Dirty/clogged air filter

Dirty MAF sensor

The check engine light comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. To determine the cause, the vehicle will need to be taken to AutoZone or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area.

A flashing check engine light is an indication of a severe misfire or problem that is likely to harm your engine. Immediate diagnosis and service is needed.

Some specific causes for the light to be on are:

Gas cap left off, not tightened, not installed correctly, or needs to be replaced

02 sensor

Engine misfire - error might clear itself after 3 complete warm-up cycles; not restarts, but warm-ups

At start up for a bulb check - Should not stay on

Problem in the emission system, including clogged exhaust or the catalytic converter not functioning properly

Dirty/clogged air filter

Dirty MAF sensor

The check engine light comes on and stays on when a problem is detected by the self diagnosis system of your vehicle. Generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. To determine the cause, the vehicle will need to be taken to AutoZone or a shop that has an OBD2 scanner, or for 1995 and earlier models, an OBD1 scanner, While a scanner will not give you the magic answer, it will give you a code that narrows down the problem area.

A flashing check engine light is an indication of a severe misfire or problem that is likely to harm your engine. Immediate diagnosis and service is needed.

Some specific causes for the light to be on are:

Gas cap left off, not tightened, not installed correctly, or needs to be replaced

02 sensor

Engine misfire - error might clear itself after 3 complete warm-up cycles; not restarts, but warm-ups

At start up for a bulb check - Should not stay on

Problem in the emission system, including clogged exhaust or the catalytic converter not functioning properly

Dirty/clogged air filter

Dirty MAF sensor

po455 could actually be a loose or deffective gas cap

The service light has nothing to do with the engine light. It can't be trigged by the ECM.
The service light are only trigged by one of 3 counters (time since last service, engine hours or mileage).

The service light are easy to reset if you got a YM1999-2000 car.
1. Put the ignition on to pos.1 and press down the trip reset button on the instrument cluster and keep it depressed.
2. Put the ignition on to pos.2,
3. When the service light starts to flash then release the trip reset button. Now you have reset the service reminder lamp.

You need to read out the DTC's from ECM to be able to fix the check engine light.

Ok Slow deceleration rev responce was part of the ECU software to keep the emissions down ,however if this has only just started you can try to reset the IAC valve ,the procedure is as follows.

Turn ignition key on ,unplug the IAC valve ,turn the key off ,replug the IAC valve. do this 3-4 times .Then start the engine while holding the gas pedal to 2000 rpm ,then slowley let the go of the gas pedal till the engine idles .

The IAC valve is located on the throtle body and has 4 wires to it.

Sometimes the throtle body needs to be cleaned and then reset.

key off, push in and hold trip odo, turn key to position 2 ( all dash board lights are now on) DONT START the car, KEEP the trip button pushed in, start the car IMEDIATELY the service light starts to flash, then release the trip odo button. Sometimes takes a couple of goes.

noisy v v t