How to Replace an audi car key case G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located on the outside of the transmission, above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU utilizes this information to control fuel and boost. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used to link with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is so it can activate spark and injectors accordingly.

If this sensor fails, the ECU will display a P00160 error message. This indicates that the Crank Shaft is out of alignment with the Intake Camshaft. It could also indicate an issue with the chain or a jumpy chain link in the upper chain. The code will not appear without the additional information provided by other sensors (G4 or G40).

Testing can be a bit difficult since there are two connector pins and they serve different purposes but the best method to test it is to measure resistance between the sensor and the ECU. If the sensor is operational, it should be reading around 1000 ohms. Examine for signs of coolant or oil in the connector bay if there are problems with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a massive decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. Today, i pulled out the spark plugs. Three were drenched with gazoline the fourth was dry. I put a piece of tissue over each injector hole, and when I start the engine without sparks, the 3 with gazoline jump out. The 4th one stays shut. I tried to test the ground connections of ECU pins 14,30, and 48/55. I got 0ohm. I assume that the problem is elsewhere.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is not plugged in and is running fine when it is plugged in, but still has intermittent misfire issues at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of that is -49c even after unplugging it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is zero.

I don't know what to do. I think I've all other possibilities out. However, i'm afraid that I might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sender is identical to the G4 and they both work in the 80, 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or at a parts store. It is easy to test them - just put your DMM into resistance mode and audi car key case determine the distance between pins 1 and 2 (with the bump on the connector's edge facing upwards). They must be infinite Ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know the position and speed of the crankshaft to determine timing of the fuel injector, etc. In order to do this it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner that can cause the engine to shut down.

A malfunctioning G28 sensor could result in an inaccurate speed counter for the gearbox or a gearbox that shifts faster than normal, or a misfire in the gear. If you experience any of these issues it is likely that your sensor is failing and needs replacing. They're inexpensive and easy to locate particularly in the case of a Bosch sensor like ours. You can also choose the GM version of this part is also a good choice.

5. Tachometer

A damaged engine sensor could cause a variety of issues in your vehicle. It's an essential component of the transmission of your new audi keys since it sends information to the ECU on how fast or slow the engine is turning. If this sensor fails, it could affect the performance of 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 transmits an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to regulate the amount of fuel and boost, and also timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection to pin T6a/1 (trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see the resistance to be around 1000 ohms between these two points. This part is common across the audi remote key 80-100-200-RS2 model, ranging from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du So, you may find some good ones in wrecking yards.