Question about 1994 Geo Metro

1 Answer

94 Automatic Geo Metro 3 Cyl. Map Sensor - EGR Valve

My mechanic tells me the diagnostic computer gave him codes for the EGR Valve and the Map sensor, which triggered the check engine light. He tells me both will need to be replaced before the light will go off.

Trying to budget as I am a college student and know nothing about cars. Which one should I budget to repair 1st? He also mentioned the EGR silinoid (spelling?) may be the 'real' problem with the EGR valve.

Note- I take really good care of my car, tune ups, engine steamed, oils changes etc.

Posted by on


1 Answer

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Expert
  • 61 Answers

Unfortunately, both of these items are equally important and repairs can't normally be avoided by taking care of your car.

Your MAP (Mass Air Pressure) Sensor measures intake manifold vacuum pressure to help control the air and fuel mixture and timing. It contains a pressure-sensitive element that connects to an electronic circuit, generating a signal that changes with pressure changes in the manifold.

Your EGR (Exhaust Gas Recirculation) valve recirculates exhaust gases through the intake manifold to be burned again, cooling peak combustion temperature. Dilutes the air and fuel mixture to keep the nitrogen oxide emissions within breathable limits. And yes, it could very well be that the EGR solenoid that is causing the issue.

Both units effect your vehicle's fuel/air mixture. This is important because your vehicle running lean/rich can cause "snowball" problems. For example, a faulty EGR can cause the vehicle to run rich/lean. If not repaired, in time, the exhaust caused by the wrong rich/lean fuel mixture can damage the O2 sensors and/or catalytic converter.

If I had to pick, I'd start with your MAP Sensor. One guess I would have is that your MAP Sensor failed and made your vehicle start burning the wrong fuel/air mixture. Assuming I'm right, this could have damaged the EGR Valve. So, I see no reason to replace the EGR Valve alone, just so it too can be damaged by the poor fuel/air mixture caused by the still-faulty MAP Sensor. If your lucky, you may see the faulty EGR code disappear once your MAP Sensor is replaced.

Hope this helps and good luck!

Posted on Jan 12, 2009

  • joycelyn reid Jan 28, 2013

    well thanks again my car is only like this first thing in morning lumpy and smokey ,i have had a code which was egr valve .also cleaned manifold flaps and mapsensor,no code now but still have the problem



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

2 Answers

Where is the location of the camshaft position sensor ? aka: CMP.

images for 1997 geo metro camshaft position sensor

1993 Geo Metro Camshaft Position Sensor Unraveled ...

? 5:18
Apr 8, 2015 - Uploaded by Jeff Dean
This is Part One of a series where I document my troubles with the Camshaft Position Sensor. This first

Sep 18, 2015 | 1997 Geo Metro

1 Answer

Hi, I'm still having problems with my 1993 chev

Hi, these codes indicate both the MAP sensor and the EGR valve. You will need to troubleshoot a bit to see exactly what is wrong. It's possible a vacuum leak could cause both of these codes. I have pasted a procedure to check the MAP sensor below using a voltmeter. If you can run this test and tell me the results, it will help to diagnose the problem. You should also check all of the vacuum hoses, including the ones from the intake manifold to the EGR solenoid and from the solenoid to the EGR valve. The run some jumper wires from the battery to the EGR solenoid pins to see if the solenoid clicks open.

TESTINGSee Figures 3, 4 and 5
  1. Backprobe with a high impedance voltmeter at MAP sensor terminals A and C.
  2. With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
  3. If the voltage is not as specified, either the wiring to the MAP sensor or the ECM may be faulty. Correct any wiring or ECM faults before continuing test.
  4. Backprobe with the high impotence voltmeter at MAP sensor terminals B and A.
  5. Verify that the sensor voltage is approximately 0.5 volts with the engine not running (at sea level).
  6. Record MAP sensor voltage with the key ON and engine off.
  7. Start the vehicle.
  8. Verify that the sensor voltage is greater than 1.5 volts (above the recorded reading) at idle.
  9. Verify that the sensor voltage increases to approximately 4.5. volts (above the recorded reading) at Wide Open Throttle (WOT).
  10. If the sensor voltage is as specified, the sensor is functioning properly.
  11. If the sensor voltage is not as specified, check the sensor and the sensor vacuum source for a leak or a restriction. If no leaks or restrictions are found, the sensor may be defective and should be replaced.


Fig. Fig. 3: Location of the MAP sensor-TBI system shown


Fig. Fig. 4: Probe the terminals of the MAP sensor to check for proper reference voltage


Fig. Fig. 5: Manifold Absolute Pressure (MAP) sensor wiring diagram

EGR solenoid:

EGR valve:

Sep 23, 2011 | 1993 Chevrolet K1500

1 Answer

94 geo metro, cleaned egr valve and replaced gasket..still missing and losing power on acceleration any ideas?

O2 Sensors with over 100,000 miles on them

Dirty MAF Sensor

Old Spark Plugs

Ignition Problems

Blocked gas filter or blocked exhaust converter

Exhaust system leaks before converter

TPS Sensor

Sep 20, 2011 | 1995 Geo Metro

2 Answers

My 94 geo metro runs very rough and has

you should check a throttle body valve or purge valve, choke valve

Feb 14, 2010 | 1994 Geo Metro

4 Answers

Insufficient egr flow, already replaced egr valve and purge valve canister

I too replaced the egr valve and was discouraged that the check engine light came back on with the same "insufficient flow" code. I took it to my mechanic to put it on the monster diagnostic machine. It said "check all vacuum line, and or map sensor". After looking real close we found a melted vacuum tube, and a cracked vacuum angle connector. Replaced both vacuum pieces, reset the codes, and good to go. If that fails than the next thing is the map sensor, that tells the EGR valve what to do.

Jan 12, 2010 | 2002 Chevrolet Impala

2 Answers

Starts and dies on acceleration then will not run

crank shaft position sensor is most likely cause. Do check ignition and fuel pump relays with an ohmmeter to make sure they are not faulty. Check power to ignition module. You can also check crank sensor with the ohmmeter. Check all vacuum hose and also check throttle position sensor.

Nov 15, 2009 | 1995 Geo Metro

1 Answer

94 geo metro won't start in the cold but runs fine when it's warm

Sounds like a bad temp sensor, it has several, you need a Clymers or Chilton's repair manual, good investment if you do your own repairs! One sensor is next to the water neck just below the distributor . other is above alternator on the intake. Also there is one on the air cleaner housing that the black connector plugs to. It's late or I would look up the resistance readings for those sensors. Do you have a check engine light on? You can jump the diagnostic plug and get a code to tell you what the ECU is seeing.

Oct 01, 2009 | 1994 Geo Metro

1 Answer


I think the 97 uses a crank sensor where the 94 doesn't. (not sure) I don't see any reason you can't just leave it unhooked. I put a 92 engine in a 94 but because of the differences in the emission controls, I had to use the 94 intake and injection system. It worked out fine. Still driving it. Some advice, while you have it apart, clean the EGR valve and journals especially the ones going from the exhaust manifold to the EGR valve (driver side of motor). That is a common problem with these cars and it usually ends up ruining the engine. (My experience is with the 3 cyl model).

Feb 23, 2009 | 1994 Geo Metro

2 Answers

93 Geo Metro

As long as they are the same type of engine ( I believe they should both be 1.0L 3 cyl engines). Most parts for the Geo Metro from 1992 to 1994 interchange with out a problem.

Nov 10, 2008 | 1993 Geo Metro

Not finding what you are looking for?
1994 Geo Metro Logo

1,483 people viewed this question

Ask a Question

Usually answered in minutes!

Top Geo Experts


Level 3 Expert

79865 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Mike Gilbreath

Level 1 Expert

50 Answers

Are you a Geo Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides