Intake manifold sensor?

jetta
volkswagen

#1

What does an intake manifold sensor do and does my car NEED it or can I get away with driving with a faulty one? I was quoted a $1075 price tag and there’s no way I can pay that at the moment.


#2

It’s probably the MAP sensor to which you refer. Manifold Absolute Pressure. It’s sort of like a barometer. In fact it can be used as a barometer. Or as an altimeter. The engine computer uses it in the calculations to determine how much fuel to inject for the driving situation. It may also use it to measure the altitude, and make adjustments to the fuel mixture calculations based on that too. Without it working you’ll get some combination of a check engine light on all the time and/or inexact fuel to air mixtures. The former will prevent you from knowing if another problems crops up, and the latter will cause the engine performance to lag, and could cause problems to the cat and others of the engine innards clogging up. That would happen over time, not immediately.

It’s also possible the sensor they’re talking about is the MAF rather than the MAP. The MAF (Mass AirFlow) performs a similar function to the MAP, so the result of not having a working one would be similar.


#3

What year, model, and engine?

The sensor you refer to is probably the Manifold Absolute Pressure Sensor.
Yes, you need it. It’s one of the “engine demand” sensors that feeds a signal to the ECU’s algorithm to determine exactly how much fuel the engine needs at any given moment. It reads the “absolute pressure” in the intake manifold.

“Absolute pressure” means the pressure from zero (a perfect vacuum). The pressure in the manifold varies based upon the speed of the crankshaft (the pistons are sucking the air in past obstructions, causing a lower than ambient pressure), the position of the throttle plate (that’s a major obstruction) and some other factors. By measuring that along with some other things, the computer can determine exactly how much fuel to deliver. It changes the fuel delivery by varying the width of the pulse of fuel from the injector(s).

The price tag sounds high. I’d suggest some other quotes.
Of course there is the possibility that I’m suggesting the wrong sensor. What were the original symptoms?


#4

What’s wrong with your car that you needed this quote? Model, year, and mileage would help.

If it is the MAP sensor… I paid around $45 for an Acura CL a few weeks back. Seems there is more to it then a MAP sensor at that estimate.


#5

This may be the 2009 Jetta TDI the OP wrote about in June needing glow plugs. It may be time to put this thing out to pasture.


#6

Zero symptoms except the check engine light. It’s running great.


#7

Do you have the code # ?


#8

Daisy, we need you to tell us more about the vehicle and the symptoms. We’re all making wild guesses here. Answer some of our questions. Please.


#9

You might surf over to rockauto.com and take a look what they charge for that sensor. That’s only the parts cost of course. But it would give you an idea if the fee you mentioned above is competitive.


#10

I have a 2009 VW Jetta and I am on my 6th or 7th intake manifold. I have had to change the whole thing out so many times I forget. I know VW did an extended warranty on certain year and model cars covering the intake manifold to 120,000 miles. Don’t know if it applies to your vehicle or if it would fix the problem. I know the units can’t be repaired. They just replace the whole thing.


#11

I can’t imagine what would cause the intake manifold to repeatedly fail like that. It’s basically just a chamber that ambient temperature air flows through after all. Does VW offer any explanation?


#12

Like George, I find myself wondering exactly what it was that caused the need for a new intake manifold. Would it be possible to get an explanation? I understand if you choose not to elaborate, and respect your wishes, but I truly am curious.


#13

My apologies. I was out in the boonies for a bit sans internet.

It’s got 115 thousand miles, TDI. The code is P2015: intake manifold runner pressure sensor range/performance.

Does that help?


#14


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