How to Replace an audi smart key replacement G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the transmission's edge, above the flywheel gear. It transmits a signal the ECU via a grey wire (T55/49) which is then sent to the tachometer in the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated on the edge of transmission, directly above the flywheel ring. This sensor sends an electrical signal through the grey wire to pin T55/49. The ECU uses this information to regulate the amount of fuel and boost. It also sends signals to the G5 Tachometer located in the 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 position of the camshaft, to trigger the spark and injectors.

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

Testing is a bit tricky because there are two connector pins, and they serve different purposes but the best way to test it is to measure the resistance between the sensor and the ECU. When the sensor is fully operational, it should be reading about 1000 ohms. Examine for signs of coolant or oil in the connector bay if you are experiencing issues with this component.

2. Injectors

Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a significant decrease in power. It was like the engine was running out of gas. Or, my injectors were audi key fob not working firing. I took out the spark plugs this morning and found that 3 were soaked in gasoline, and the fourth was dry. When I start the engine, there are no sparks, i place a tissue on top of each injector hole and the 3 that were drenched in gazoline jump out but the 4th stays closed. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ I got zero ohm. I'm assuming that the issue is elsewhere.

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 problem still occurs at higher RPM. The coolant sensor (G62), even when unplugged, still shows an ice temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bar but the actual pressure is zero.

I'm not sure what to do. I think I've eliminated everything else. But i'm worried that i might have missed something. Let me know if you have any ideas! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal from the RPM sensor. The GM-style transmitter is identical 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. It is simple to test them - just switch your DMM into resistance mode and test 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) engines needs to know both the position and speed of the crankshaft to determine timing of the fuel injector, 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 of these sensors, the diagnostic scanner will show the codes that could trigger an engine shutdown.

A damaged G28 sensor can cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, or a misfire in the gear. If you are experiencing any of these issues it is likely your sensor is deteriorating and needs replacing. The good thing is that they are very cheap and readily available, especially if you're looking at an Bosch unit like ours. You can also choose the GM version of this component is also a good choice.

5. Tachometer

A damaged engine sensor could cause a number of problems in your vehicle. It is a crucial part of the audi a1 key's transmission as it sends information to the ECU about how fast or slow the vehicle's crankshaft is turning. This sensor can cause the transmission to fail and other components of the car to be affected.

The G5 engine sensor is located at the edge of the transmission, over the flywheel ring. It transmits a signal via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, as well as timig. It also transmits it to the G5 Tachometer in instrument cluster. You can determine if the sensor is in failure by examining the continuity of 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 [79]), and between pin T6a/1 as well as pin T26a/12. It should show around 1000 ohms of resistance between those two pins. This is a common component across the audi tt key fob 80, 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU so good parts could be found in wrecking yards.