Note: Recommendation: if you service your Renault 19 regularly in a car repair shop, then exhaust toxicity control (exhaust gases) refers to the volume of service work.
When performing such a test, the car is connected to a complex expensive measuring device, the printer of which prints out the measurement results for their evaluation. If individual values do not correspond to the norms, the test is failed. However, if it is passed, this means that the exhaust system is in good condition, air is not sucked into the intake manifold through leaks, the air filter is not clogged and the spark plug electrode gap is normal. Just in case, it is also necessary to check the ignition installation.
If you need to pass a "technical inspection of the vehicle" for your Renault 19, first pass the exhaust gas toxicity test.
If the Renault 19 has been used for a long time in winter only on short distances, then you should change the oil. Condensate accumulated in the oil worsens the results of exhaust gas monitoring.
Without passing the exhaust gas toxicity test, do not immediately replace any expensive design element, repeat the toxicity test in another auto repair shop. Despite the expensive measuring equipment, errors are still possible.