How to Replace an Audi Tt key programming G28 Engine Speed Sensor

In this video Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. This sensor is located at the edge of transmission just above the flywheel gear. It transmits a signal the ECU via the grey wire (T55/49) which is then sent 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 an electrical signal to ECU pin T55/49 via a grey wire. The ECU uses this information to regulate the amount of fuel and boost. It also sends signals to the G5 tachometer inside the instrument cluster.

The sensor serves as a reference for comparing with the G40 Camshaft Position Sensor. The ecu has to know when the crankshaft has reached TDC, and the position of the camshaft, so that it can activate the spark and injectors.

If this sensor fails, the ECU will display an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are out of sync and could indicate the chain is stretched or a jump link on the upper chain of timing. However the code will not be displayed on its own without additional information from other sensors (G4 and G40).

Testing is a bit challenging because there are two pins for the connector and they perform different functions however the best method of testing it is by measuring resistance between the sensor and Audi Tt Key programming the ECU. If the sensor is functional, it should read about 1000 ohms. Look for signs of coolant, or oil in the connector bay if you are experiencing problems with this part.

2. Injectors

Yesterday, while accelerating at full speed from the highway paytoll i had a big cut in power as if the engine was running out of gas or the injectors are not firing at all. I pulled out the spark plugs this morning and found that 3 were soaked with gasoline and the fourth was unclean. I put tissue over each injector hole, and when i start the engine without sparks, the 3 that have gazoline pop right out. The 4th one stays closed. I checked the ground connection of ECU pins 14,30, and 48/55. I found 0ohm. Therefore, i think the issue is elsewhere.

I also tried to reset PID but without success. The car can start when the G28 is not plugged in and is running fine when it is plugged in, but still has the intermittent misfire issue at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. Also i noticed that the gauge for oil pressure in the cockpit shows 2 bar, whereas the actual pressure is 0.0 when i rev the engine.

I don't know what to do. I think I've ruled everything else out. I'm concerned that i may have missed something. If anyone has any ideas please let me know! TIA!

3. Fuel Pump

The fuel pump of the g28 receives a signal from the RPM sensor. The GM-style sensor 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 junkyard or at a parts store. It is simple to test them: simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector end facing up). They should be infinite ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines must know both the speed and position of the crankshaft in order to make a decision about timing of the fuel injector, etc. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to achieve this. If you have a problem with either one of these, the diagnostic scanner will show codes that could cause an engine shutdown.

A failing G28 sensor can cause an inaccurate speed counter for the gearbox and a gearbox which shifts faster than normal, or a misfire while in gear. It is probable that the sensor is failing and requires to be replaced if you notice any of these symptoms. They're inexpensive and easy to locate, especially when they're a Bosch unit like ours. Alternatively, the GM version of this unit is also a good choice.

5. Tachometer

A failing engine sensor could cause a myriad of issues in your vehicle. It's a crucial component of the transmission in your audi keys replacement since it sends information to the ECU regarding how fast or slow the engine is turning. If this sensor fails, it can affect the performance of the transmission, as well as the other car's components.

The G5 engine sensor is located at the outskirts of transmission, above the flywheel ring. It transmits an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU is then able to process this signal to regulate fuel, timig and boost as well as transmitting it to the G5 tachometer in the instrument cluster. You can test the sensor for any failure by checking the continuity between it and the tachometer, between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79]) as well as between T6a/1, and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these points. This is a common feature across the audi car key 80-100-200-RS2 series, starting beginning with the 1985 MC and up to the 1997 UrS An and 1995 RS2 DU So, you may find them in wrecking yards.