Question about 1998 Chevrolet S-10 Pickup
I have a chevy s-10 1998 with a 4 cyl engine...i have replaced the ecm and both oxygen sensors along with the egr tube and thermostat and the check engine light keeps coming on reading the code p 1133 insufficient switching bank 1 sensor 1 my mechanic and i are both frustrated any ideas
The code means the sensor is staying in lean or rich mode for too long. The computer is supposed to adjust fuel mixture to make the exhaust switch back and forth from lean to rich every 10 or 20 seconds.
If the engine is not warming up the emissions system will not go into closed loop which allows the computer to make the adjustments.
Do you know if the engine is reaching normal temp ?
Any exhaust leaks upstream ?
Posted on Jan 16, 2013
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Posted on Jan 02, 2017
SOURCE: Insufficient EGR Flow problem
Specifically DTC P0401 is "Exhaust Gas Recirculation (EGR) Insufficient Flow". Now this is where we have to be careful when we read a code. In this case it is not saying the EGR valve is bad, it's saying the EGR flow is too low. Now it could be because the EGR valve is bad. Or it could be a clogged EGR tube or a broken vacuum line. This is why you have to be careful and check the whole system before you go changing parts.
The PCM tests the EGR system during deceleration by momentarily commanding the EGR valve to open while monitoring the Manifold Absolute Pressure (MAP) sensor signal. When the EGR valve is opened, the PCM should see a proportional increase in MAP. If the expected increase in MAP is not seen, the PCM notes the amount of error that was detected and adjusts an internal fail counter towards a fail threshold level. When the fail counter exceeds the fail threshold level, the PCM will set DTC P0401. The number of test samples required to accomplish this may vary according to the amount of detected flow error.
Normally, the PCM will only allow one EGR flow test sample to be taken during an ignition cycle. To aid in verifying a repair, the PCM allows twelve test samples during the first ignition cycle following a scan tool Clear Info or a battery disconnect. Between nine and twelve samples should be sufficient for the PCM to determine adequate EGR flow and pass the EGR test.
To check the system first you need to remove the EGR valve and if it is clogged or broken. If it is, clean or replace it. If it is okay, then remove the EGR inlet tube from the exhaust manifold and the EGR outlet tube from the intake manifold. If either or both are clogged, clean them out or replace them. Then check the ports in the manifolds themselves to see if they are clogged. If so, clean them out.
When you are done, disconnect the battery for about 30 seconds to clear the code and drive the car to see if the light comes back.
This should take care of the problem. If not, then you will need to put a scan tool on the car and see what the EGR control system is doing wrong and correct it.
The Valve on this car is electronic, so, unfortunately a vacuum pump will not work for testing.
If you have a scan tool, you can command the pcm to open the valve to see if the valve itself is working.There are really only4 things to go wrong with these things, PCM, wiring,the valve itself, or plugged passages. I have never seen the pcm cause this problem, or the wiring for that matter. If you say you have pulled the EGR and checked the intake passages, then I would be pretty confident in saying the the egr valve itself is bad.
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Posted on Mar 18, 2009
the sensor is on you exgsaust pipe under the truck. if you slide under the truck behind the front tire. look at the pipe. you will see a sensor on the pipe with some wires coming out.
Posted on Feb 09, 2010
SOURCE: 2000 chevy silverado 1500 4.8
It could be that your knock sensor circuit is working perfectly.You may have a knock that it is reading for long periods.
Try running it disconnected, and see if there is a clatter or knock when accelerating lightly.
You could have a vacuum leak.
Posted on Feb 25, 2010
If all connections are good "dry, tight, no corrosion" then yes. It should be a defective sensor. These sensors are piezo sensors and create a voltage when sensing a knock. A bank refers to a side on a V style engine, 2 refers to the rear sensor on your bank 2. Bank 1 should be the side with cylinder #1 which should be the cylinder closest to you on one of the sides. So your looking for the rear sensor on the opposite side.
Posted on Jun 13, 2010
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