How to Replace an audi key copy G28 Engine Speed Sensor

In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. The sensor is located near the transmission’s edge over the flywheel gear. It transmits a signal to the ECU via an uncolored wire (T55/49) which is then sent to the tachometer within the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, just above the flywheel ring. The sensor sends an electrical signal through the grey wire to pin T55/49. The ECU then utilizes this information to regulate the boost, fuel, and timig. It also sends an alert to the G5 Tachometer in instrument cluster.

The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu has to be aware of when the crankshaft has reached TDC, and the location of the camshaft so that it can activate the spark and audi replacement key service injectors.

If this sensor fails, the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync and possibly indicating chain stretch or a jumped link on the upper timing chain. However the code will not appear on its own, without additional information from other sensors (G4 and G40).

Testing is a bit tricky as there are two different pins for the connector and they serve different purposes but the best method of testing it is to measure resistance between the sensor and the ECU. When the sensor is fully operational, it should read approximately 1000 ohms. If you’re having issues with this sensor, look for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday accelerating full speed from highway paytoll, I experienced an abrupt drop in power as if the engine was running out of gas or the injectors are not firing at all. Today, i pulled out the spark plugs, 3 were drenched with gazoline the 4th one was dry. When i crank the engine without sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th one stays closed. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. I get zero Ohm. I assume that the problem is in another location.

I also tried to reset the PID with no success. The car is able to start when the G28 is not plugged in and is running fine when it is connected however it has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c, even if I unplug it. Also, i noticed that the gauge for oil pressure in the cockpit is showing 2 bar while the actual pressure is 0.0 when I crank up the engine.

I’m not certain what to do, as i feel i have pretty much ruled out everything else. But i’m worried that I may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sender is the same as the G4 and both are used in the 80 100 200, UrS and RS2 cars which is why you can easily locate one at a wrecking yard or in a local parts store. It is easy to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump on the connector’s edge facing upwards). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY, and ADU) engines have an ECU that must know the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, for example. To accomplish this, it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger the engine shutting down.

A damaged G28 sensor can cause an inaccurate gearbox speed counter or a gearbox that shifts more quickly than normal, and/or a misfire in the gear. It is likely that the sensor is failing and needs to be replaced if you notice any of these signs. They are cheap and easy-to-find especially if they’re a Bosch model like ours. If you prefer, GM’s version of this part is an excellent choice.

5. Tachometer

A failing engine speed sensor audi car key case could be the cause of many problems in your vehicle. It’s a vital component of the audi key fob Replacement cost‘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 components of the car to be affected.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU uses this signal to regulate fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer in instrument cluster. You can check the sensor for any failure by checking the continuity between it and the tachometer, between the 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. It should show approximately 1000 ohms resistance between these two points. This is a common feature across the audi spare key 80-100-200-RS2 series, starting from the 1985 MC all the way up to the 1997 UrS AN and 1995 RS2 DU, so you might find them in wrecking yards.