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CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

Posted by ggalv (My Page) on
Sat, Oct 3, 09 at 15:56

Right now my friend's car has the check engine light on. It is marking the Knock Sensor, Oxygen Sensor, Transmission Sensor and Airflow meter sensor (maybe circuit).

Right now there is money issues. Here are few questions I am trying to find out.
1. Is the work required to fix these parts independent or can some jobs be done at the same time. Such as when they replace the Knock Sensor do they have easier access to the Transmission Sensor (or transmission parts inside the transmission) OR are these jobs totaly independent of each other. What about the Oxygen Sensor and Airflow meter?

2. Also, how critical are these jobs? Which one should she take care right away and are there some that she can do in the future?

THANKS - Really appreciate your advice


Follow-Up Postings:

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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

First, there are ALWAYS money issues, that's why having it diagnosed correctly, and repaired correctly the first time is so important. Just this week I repaired a Chrylser LHS for a transmission that would not shift (stuck in failsafe, second gear) where the owner went out, purchased a transmission without having it tested first, and went to a shop and told them he wanted it installed. They were slow, so the did it for him, only for him to still have the car displaing the same symptom. Now did it need the tranny? I have no way to know now, but to get the transmission computer to control the transmission I had to locate a repair a break in a wire between the two.

If you want to assume that he didn't actually need the transmission, then he paid about $1500 more than he needed to to have the car repaired.

So that being said, what codes are setting in the computer? What symtpoms is the car displaying, and what make, model, and year is it?


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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

The car is a 1996 Nissan Maxima. We took it to a shop and they said that it was marking the Knock Sensor, Oxygen Sensor, Transmission Sensor and the Air Flow Meter (or Air Flow Meter Circuit). Sorry don't have the computer codes.

Right now the major sympton is that the car is overheating. When we look at the radiator we notice that it is missing coolant. When we put coolant then the car seems to work fine. But then again later on it overheats - because it is missing water again.

Appreciate your help.


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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

Obviously you are losing water. Only two ways for that to happen, a leak or running hot and boiling it away. Park on concrete and check for a leak. If none, something is causing water loss through overheating. Two most likely culprits are bad thermostat or plugged radiator. Replacing the thermostat is a cheap diagnostic...do it. After 12 years, the radiator is suspect. A cheap, shade tree fix that still works well today on dirty radiators is to drain the radiator, then refill with fresh water. Then remove the clamp on the upper hose at the radiator. Put some cardboard in a position to keep sprayed water off any electrical stuff (alternator, distributor, starter, etc.). Then place a piece of cardboard in front of the radiator to block airflow. Keep everyone clear...this sprays boiling water (do this outside) and start the engine and let it idle. Wait in the driver's seat for the top hose to blow off. When it does, shut off the engine. What happens here is that the water will get to above-boiling temperature and build up pressure. Remember, your pressure cap is still protecting the system against overpressure. When it gets high enough, the hose will blow off. At that point, all the water in the system will immediately turn to steam. This will 'steam clean' the internals..you'll find residue all over once the show is over. As long as you shut the engine down when it 'pops', you won't hurt anything. Wait until it cools down...look in the radiator and you'll see what looks to be a brand-new inside. Refill with water and you have a clean system. Never use any of the 'cleaners' sold for the purpose...they only loosen up debris that then can clog the radiator and heater core further.


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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

I have parked the car after running it for awhile and looked for any leaks but I have not seen any. This radiator was replaced about 3/4 years ago. When I touch the main water hose from the radiator it feels like water is running - would that me that the thermostat is good? Do you still recommend replacing the thermostat? Appreciate your advice.


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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

If you have an internal coolant leak, you will likely not find anything underneath the car. Internal as in say, intake manifold, block, heads, gaskets.


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RE: CheckEngine (Knock, OZ, Tranny Silinoid/Sensor, AirFlow Meter

Been looking to the location of the knock sensor, Is it a hard fix or may need special and professional help from an expert?

Here is a link that might be useful: Knock Sensor


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