How to Replace an Audi G28 Engine Speed Sensor

Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. This sensor is located near the edges of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

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

The sensor is used as a reference to correlate with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and the location of the camshaft so that it can activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 error message. This means that the Crank Shaft is not in line with the Intake Camshaft. It could also be a sign of a chain stretch or a jumpy chain link in the upper chain of timing. The code won't appear without the additional information supplied by other sensors (G4 or G40).

It can be a bit difficult to test because there are various pins on the connector and audi replacement key cost each has its own functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. It should read approximately 1000 ohms if the sensor is at full operation. If you're having issues with this component, look for signs of oil or coolant in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll i had an abrupt drop in power as if the engine was running out of gas or the injectors are not firing at all. I took out the spark plugs this morning and found that 3 were drenched in gasoline and the fourth was dry. When I crank the engine without sparks, i place a tissue on the top of each hole in the injector and the 3 drenched with gazoline leap out, however the 4th stays closed. I inspected the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero Ohm. I'm assuming the issue is elsewhere.

I also tried to reset the PID without success. The car is able to start if the G28 is disconnected and it runs perfectly when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.

I'm not certain what to do, i believe that i've eliminated everything else. However, i'm afraid that I may have missed something. Let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or parts store. Testing them is easy by putting your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines requires to be aware of the speed and position of the crankshaft in order to make a decision about timing of fuel injectors, etc. To do this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go badly, you will see codes on the diagnostic scanner that can lead to engine shutdown.

A damaged G28 sensor could result in an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or a misfire while in the gear. If you experience any of these issues, it is most likely that your sensor is going bad and requires replacement. The good news is they are very cheap and easily accessible, especially when you're looking at an Bosch sensor, which is what ours are. If you prefer, GM's version of this part is an option.

5. Tachometer

A damaged engine sensor could cause a variety of issues within your vehicle. It's an essential component of the transmission of your audi key fob replacement cost, as it transmits information to the ECU on how fast or slowly the engine is spinning. When this sensor fails, it will disrupt the performance of the transmission as well as the other car's components.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It sends signals via an uncolored wire to the ECU pin T55/49. The ECU then uses and processes the signal to control fuel, timig, and boost and then sends it on to the G5 tachometer in the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer, between the ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should detect the resistance to be around 1000 ohms in these areas. This is a common feature across the audi Replacement Key cost 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS AN and the 1995 RS2 Du So, you may find some good ones in wrecking yards.