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 on the edge of the transmission just above the flywheel ring 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 grey wire is located on the outside of the transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends an indication to the G5 Tachometer in instrument cluster.
The sensor is used as a reference for comparing with 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 accordingly.
If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain stretching or a jump link on the upper chain of timing. However, the code won't be displayed on its own without additional information from other sensors (G4 and G40).
Testing is a bit tricky since there are two pins for the connector and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully functional, it should read about 1000 ohms. If you're experiencing issues with this sensor, look for evidence of coolant or oil in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a significant decrease in power. It was as if the engine had run out of gas. Or my injectors were not firing. Today, i pulled out the spark plugs, three were drenched in gazoline, the fourth one was dry. When i crank the engine without sparks, i place a tissue on top of each injector hole and the 3 drenched with gazoline leap out, however the 4th stay shut. I tested the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got 0ohm. I assume that the problem is somewhere else.
I also tried to reset the PID without success. The car can start if the G28 is unplugged and runs fine when it is plugged in, but still has intermittent replacement audi key misfire issues at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar when the actual pressure is 0.0 when i rev the engine.
I'm not sure what to do. I feel like i've pretty much ruled everything else out. But i'm worried that i might have missed something. Let me know If you have any suggestions! TIA!
3. Fuel Pump
The fuel pump in the g28 receives a signal from the RPM sensor. The GM-style sensor is the same as the G4 and both are more info used in audi a4 spare key the 80 100, 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or at a parts store. Testing them is easy to do - just put your DMM in resistance mode and take measurements between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.
4. ECU
The audi keys ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed the crankshaft to determine timing of fuel injectors, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either of these, the diagnostic scanner will show codes that could cause an engine shutdown.
A failing G28 sensor could result in an inaccurate gearbox speed counter and a gearbox which shifts faster than normal, and/or a misfire in gear. It is possible that the sensor is failing and requires to be replaced if you experience any of these signs. The good news is they are quite affordable and readily available particularly if you're looking at a Bosch sensor, like ours. You can also choose the GM version of this part is also a good choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your vehicle. It is a crucial part of your Audi's transmission, as it sends information to the ECU about how fast or slow the car's crankshaft is rotating. This sensor could cause the transmission to malfunction and other car components to be affected.
The G5 engine speed sensor is located on the outside of the transmission, above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via an uncolored wire. The ECU uses this signal to regulate fuel and boost, and also to timigrate. It also relays it to the G5 Tachometer in instrument cluster. You can check the sensor for failure by checking continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster audi a3 key replacement near me connection via pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. It should show approximately 1000 ohms resistance between those points. This is a common part that is found across the Audi 80 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.