How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches how to replace the G28 Engine Speed Sensor. This sensor is located at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49), then to the tachometer located in the instrument cluster.
1. Engine Speed Sensor
The sensor is located at the edge of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through an uncolored wire. The ECU utilizes this information to control fuel and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor is used to link with the G40 Camshaft position Sensor. The ecu must know when the crankshaft has reached TDC, and where the camshaft lies to trigger the spark and injectors.
If this sensor fails the ECU will display a P00160 code which means the Crank Shaft and Intake Camshaft aren't in sync and could indicate chain stretch or a jumped link on the upper chain of timing. The code will not appear without the additional information provided by other sensors (G4 or G40).
Testing is a bit tricky because there are two connector pins and they serve different purposes but the most effective way to test it is by measuring resistance between the sensor and the ECU. It should read around 1000 ohms when it is operating at its maximum. If you are having problems with this component, look for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday accelerating full speed from highway paytoll i had an abrupt drop in power like the engine is running out of gas or injectors aren't firing at all. I pulled out the spark plugs this morning, 3 were drenched in gasoline and the fourth was dry. I put a piece of tissue over each hole in the injector and when I start the engine without sparks, the 3 with gazoline jump right out. The fourth one remains shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got 0ohm. So i assume the problem is in another place.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it is running fine with the G28 plugged in. However, the intermittent misfire problem continues to occur at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of -49c even when i unplug it. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I think I've eliminated everything else. I'm concerned that i may have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent by the RPM sensor. The GM-style transmitter is identical to the G4 and they both work in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or from a parts store. Test them out - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft to make decisions about timing of the fuel injectors, etc. To accomplish audi a1 car key , it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these goes bad you will get codes on the diagnostic scanner that could cause engine shut down.
A damaged G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or a misfire while in the gear. It is likely that your sensor is failing and needs to be replaced if you notice any of these symptoms. They're cheap and easy to find particularly when they're a Bosch sensor like ours. Alternatively, GM's version of this part is an excellent choice.
5. Tachometer
A failing engine sensor could cause a number of problems in your vehicle. It is an important part of the transmission of your Audi because it relays information to the ECU on how fast or slow the car's engine is turning. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine speed sensor is situated on the edge of the transmission just above the flywheel ring gear and sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to control the flow of fuel and boost and also to timigrate. It also transmits it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. Also, you can verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 as well as pin T26a/12. You should see the resistance to be around 1000 ohms in these areas. This is a common feature across the Audi 80-100-200-RS2 model, ranging beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 Du You may also find some good ones in wrecking yards.