How to Replace an audi replacement key cost uk G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It sends a signal to 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 located on the edge of transmission, just above the flywheel ring. The sensor transmits a signal via the grey wire to pin T55/49. The ECU then uses this information to control the flow of fuel, timig and boost. 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 must be aware when the crankshaft is TDC and the location of the camshaft so it can trigger spark and injectors according to the situation.

If this sensor fails, the ECU will display the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync, possibly indicating the chain stretching or a jump link on the upper chain of timing. The code won't appear without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging as there are two different connector pins, and they serve different purposes but the most effective method of testing it is to measure resistance between the sensor and the ECU. It should read approximately 1000 ohms when it is operating at its maximum. If you're experiencing issues with this part, check for evidence of coolant or oil in the connector bay.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced an abrupt drop in power like the engine is running out of gas or injectors aren't firing any more. This morning i pull out the spark plugs, three were soaked with gazoline and the fourth was dry. When I start the engine with no sparks i put tissue on top of each injector hole and the 3 that were drenched in gazoline leap out, however the 4th one stays closed. I tested the ground connection of ECU pins 14,30 and 48/55. I got 0ohm. Therefore, i think the issue is in another place.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is disconnected and is running fine when it is plugged in however it has the intermittent misfire issue at higher RPM. The temperature sensor for coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar while the actual pressure is 0.0 if i crank up the engine.

I'm not certain what to do, i believe that i've ruled out everything else. But i'm worried that I might have missed something. Please let me know should you have any suggestions! TIA!

3. Fuel Pump

The fuel pump in the g28 receives signals from the RPM sensor. The GM-style sensor is identical to the G4 and both function 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 at the connector's end facing up). They should be infinite Ohms.

4. ECU

Our 20vt turbo (3B, AAN, ABY and ADU) engines are equipped with an ECU that has to know the position and speed of the crankshaft to make decisions regarding timing of the fuel injector, for example. It makes use of a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either one of these, the diagnostic scanner will show codes that could cause an engine shut down.

Some of the signs of a failing G28 sensor are an inaccurate rev counter in the gearbox, gears shifting quicker than normal, and/or a misfire when you are in gear. If you have any of these issues, it is likely your sensor is going bad and requires replacement. The good news is that they are very cheap and readily available particularly in the case of a Bosch model, like ours. You can also choose the GM version of this component is also a great option.

5. Tachometer

A malfunctioning engine speed sensor could be the cause of many issues in your vehicle. It is an important part of the transmission in your audi keyfob, as it transmits information to the ECU on how fast or slowly the engine is spinning. If this sensor fails, it will cause problems for 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 an electrical signal through an uncolored wire to the ECU pin T55/49. The ECU then uses and processes this signal to regulate fuel, timig and boost and then transmitting it to the G5 tachometer in the instrument cluster. You can test for sensor failure by checking continuity from the sensor to the tachometer. You can also verify continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79trace [79]), and between pin T6a/1 and pin T26a/12. You should see approximately 1000 ohms resistance between those points. This is the same across the audi key fob 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 DU So, you may find some good ones in wrecking yards.