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How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The sensor is located at the edge of the transmission, above the flywheel ring gear G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 using a grey wire. The ECU uses this information to control fuel and boost. It also sends an alert to the G5 Tachometer within the instrument cluster.

The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu must be aware when the crankshaft is TDC and where the camshaft is located so that it can trigger spark and injectors accordingly.

If this sensor fails to function, the ECU will display a P00160 error code. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate the possibility of a chain stretch or jumpy chain link in the upper timing chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).

It can be a bit difficult to test because there are several pins on the connector and each one has different functions. The best way to do it is by measuring the resistance between the ECU and the sensor. If the sensor is functional, it should read approximately 1000 ohms. Examine for evidence of coolant or oil in the connector bay if you have problems with this part.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had a big cut in power like the engine is running out of gas or the injectors aren't firing any more. I took out the spark plugs this morning, three were drenched in gasoline and the fourth was dry. When I crank the engine without sparks i put tissue on the top of each of the injector holes, 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 found zero ohm. I assume that the problem is somewhere else.

I also tried to reset the PID but with no luck. The car will start when the G28 is disconnected, but it is running fine with the G28 connected. However the intermittent misfire issue still occurs at higher RPM. The coolant sensor (G62), even when unplugged, still shows temperatures of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 if i crank up the engine.

I'm not sure what to do, but i think i've pretty much ruled out everything else. However, i'm afraid that I might have missed something. If anyone has suggestions, please let me know! TIA!

3. Fuel Pump





The fuel pump of the g28 receives signals from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender, and both operate on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. It is simple to test them - simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the position and speed the crankshaft to determine fuel injector timing, etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could cause an engine shutdown.

A failing G28 sensor could result in an inaccurate speed counter for the gearbox or a gearbox that shifts more quickly than normal, or a misfire while in the gear. If you are experiencing any of these issues it is likely that your sensor is going bad and requires replacement. The good thing is that they are quite affordable and easily accessible particularly in the case of an Bosch unit which is what ours are. If you prefer, GM's version of this part is an option.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for numerous problems in your vehicle. audi convenience key 's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is turning. If the sensor fails, it will cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends a signal via gray wire to ECU pin T55/49. The ECU then processes this signal to regulate fuel, timig, and boost, and also transmitting it to the G5 tachometer in the instrument cluster. You can determine if the sensor is in failure by checking 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 and pin T26a/12. You should see a resistance of approximately 1000 ohms between these two points. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find good ones in wrecking yards.