How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is located at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU via the grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends an alert to the G5 Tachometer in instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors in the right way.
If this sensor fails the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper timing chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
It's a bit tricky to test since there are several pins on the connector, and each has its own functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when the sensor is in full operation. Look for evidence of coolant or oil in the connector bay if you have issues with this component.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at a high speed, i noticed a huge decrease in power. It was as if the engine had run out of gas. Or, my injectors weren't firing. This morning i pull out the spark plugs, 3 were drenched with gazoline the fourth was dry. When i crank the engine, there are no sparks i put tissue on the top of each hole in the injector, the 3 drenched with gazoline jump out but the 4th stays closed. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got zero ohm. So i assume the problem is in another place.
I also tried to reset PID without success. The car will start when the G28 is disconnected, but it runs fine with the G28 plugged in. However the intermittent misfire issue still occurs at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature of -49c, get more info even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.
I'm not sure what to do, but i think i've pretty much completely ruled out all other possibilities. However, i'm afraid that i might have missed something. Let me more info know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or at a parts store. It is simple to test them - just switch your DMM into resistance mode and test the distance between pins 1 and 2 (with the bump at the connector's end facing up). They must be infinite ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY) engines requires to know the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these sensors, the diagnostic scanner will display the codes that could trigger an engine shutdown.
A failing G28 sensor could cause an inaccurate gearbox speed counter and a gearbox which shifts more quickly than normal, and/or a misfire while in the gear. If you are experiencing any of these problems, it is likely that your sensor is going bad and should be replaced. They're inexpensive and easy to locate, especially when they're a Bosch sensor like ours. Alternatively, the GM version of this unit is also a good choice.
5. Tachometer
A malfunctioning engine get more info speed sensor could be the reason behind many problems in your vehicle. It's a crucial component of the transmission in your Audi since it sends information to the ECU regarding how fast read more or slowly the car's engine is turning. When this sensor fails, it can cause problems for the transmission, as well as the rest of the car's components.
The G5 engine sensor is located at the edge of transmission, above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig and boost and then transmitting it to the G5 Tachometer located in the instrument cluster. You can test for sensor failure by examining the continuity of the sensor to the tachometer. You can also verify continuity between pin T55/49 of the check here ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 and pin T26a/12. It should show around 1000 ohms of resistance between these two points. This is a typical part across the Audi 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.