How to Replace an audi key G28 Engine Speed Sensor

Charles the Humble Technician shows you how to replace the G28 Engine Speed Sensor. This sensor is located on the outside of the transmission over the flywheel gear. It sends a message to the ECU via the grey wire T55/49 and then to the tachometer in the instrument cluster.

1. Engine Speed Sensor

It is located on the outside of the transmission above the flywheel ring gear, the G28 Engine Speed Sensor sends signals to ECU pin T55/49 via the grey wire. The ECU then uses this information to control the boost, fuel, and timig. It also sends a signal to the G5 Tachometer located in the instrument cluster.

The sensor is used as a reference for comparing with the G40 Camshaft Position Sensor. The ecu must be aware when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors accordingly.

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

Testing is a bit tricky as there are two different pins for the connector and they perform different functions but the best method of testing it is to measure the resistance between the sensor and the ECU. It should read about 1000 ohms if the sensor is in full operation. If you're experiencing issues with this component, look for audi q7 key evidence of oil or coolant in the connector bay.

2. Injectors

Yesterday, when accelerating from highway paytoll at maximum speed, i noticed a huge drop in power. It was like the engine was running out of gas. Or my injectors were not firing. This morning i pull out the spark plugs, 3 were drenched in gazoline, the fourth was dry. When I start the engine with no sparks, I put a piece of tissue on the top of each hole in the injector and the 3 that were drenched in 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. So i assume the problem is somewhere else.

I also tried to reset the PID with no success. The car will start when the G28 is disconnected and it runs perfectly when it is plugged in, but still is experiencing intermittent misfires at higher RPM. The coolant sensor (G62) even if it is not plugged in, shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit shows 2 bar when the actual pressure is 0.0 when i rev the engine.

I'm not certain what to do, i feel i have pretty much ruled out everything else. However, i'm afraid that I might have missed something. Please let audi replacement key service near me know If 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 the same as the G4 and they both work in the 80 100, 200, UrS and RS2 cars so you can easily find one at a wrecking yard or in a local parts store. Testing them is easy - put your DMM in resistance mode and measure the resistance between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They must be infinite ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that must know the speed and position of the crankshaft to make decisions about fuel injector timing etc. In order to do this it uses a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you encounter a problem with either of these sensors, the diagnostic scanner will display codes that could lead to an engine shut down.

Some of the signs of a malfunctioning G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or a misfire when you're in gear. If you have any of these problems, it is likely that your sensor is going bad and should be replaced. They're inexpensive and easy to locate especially when they're a Bosch unit like ours. Alternately, GM's version this part would be an option.

5. Tachometer

A failing engine sensor could cause a variety of issues in your car. It's an essential component of the audi key programmer's transmission since it relays information to the ECU about how fast or slow the car's crankshaft is rotating. This sensor could cause the transmission to fail and other car Key Cover audi components to be affected.

The G5 engine speed sensor is situated on the outside of the transmission above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via a grey wire. The ECU then processes this signal to regulate the flow of fuel, timig and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can check for sensor failure by checking continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]), and between pin T6a/1 as well as pin T26a/12. It should show approximately 1000 ohms resistance between those two pins. This part is common across the audi car key cover 80-100-200-RS2 series, starting from the 1985 MC up to the 1997 UrS An and 1995 RS2 DU, so you might find some good ones in wrecking yards.