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How to Replace an audi A5 key fob G28 Engine Speed Sensor

In this video Charles the humble mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is situated at the edge of transmission just above the flywheel gear. It transmits a signal the ECU via the 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 an electrical signal to ECU pin T55/49 using a grey wire. The ECU then uses this information to control fuel, timig and boost. It also sends an indication to the G5 Tachometer in instrument cluster.

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

If this sensor fails the ECU will throw an error code P00160 which indicates that the Crank Shaft and Intake Camshaft are not in sync, possibly indicating chain stretch or a jumped link on the upper timing chain. The code won't show without the additional information provided by other sensors (G4 or G40).

Testing is a bit challenging since there are two 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 about 1000 ohms when the sensor is operating at its maximum. Check key for audi evidence of coolant or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, when accelerating from highway paytoll at full speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or, my injectors were not firing. Today, i pulled out the spark plugs, 3 were drenched with gazoline the fourth was dry. When I start the engine without sparks, i place a tissue on the top of each hole in the injector, the 3 drenched with gazoline pop out, but the 4th one stays shut. I inspected the ground connection on ECU pins 14/55,30/55 and 48/55 i get zero ohm. I assume that the problem is in another location.

I also tried to reset the PID but with no luck. The car can start when the G28 is not plugged in and it runs perfectly when it is plugged in however it is experiencing intermittent misfires at higher RPM. The coolant temperature sensor (G62) shows the wrong temperature value of -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar when the actual pressure is zero.

I don't know what to do. I think I've all other possibilities out. But i am afraid I may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump on the g28 is activated by a signal sent 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 a spare in a wrecking shop or a 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 end facing upwards). They must be infinite ohms.

4. ECU

The ECU of our 20vt turbo (3B AAN ABY) engines requires to be aware of the position and speed of the crankshaft in order to make a decision about timing of the fuel injector, etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these go wrong, you will receive codes on the diagnostic scanner that could cause engine shut down.

A damaged G28 sensor could result in an inaccurate speed counter for your gearbox, a gearbox that shifts faster than normal, or an unfire when in the gear. It is possible that your sensor is failing and needs to be replaced if you notice any of these symptoms. They're inexpensive and easy to locate especially when they're a Bosch model like ours. Alternately, the GM version cost of audi key replacement this unit is also a great option.

5. Tachometer

A failing engine speed sensor could be a cause for a slew of issues with your vehicle. It's a crucial component of the transmission in your replacement audi key cost because it relays information to the ECU about how fast or slow the engine is turning. If this sensor fails, it can cause problems for the transmission and the rest of the car's components.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends an electrical signal through a gray wire to the ECU pin T55/49. The ECU uses this signal to control fuel and boost, as well as timig. It also transmits it to the G5 Tachometer inside the instrument cluster. You can determine if the sensor is in failure by examining the continuity of the sensor to the tachometer. Additionally, you can check continuity between pin T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 and pin T26a/12. You should observe approximately 1000 ohms resistance between those two pins. This is a standard part that is found across the audi key replacement cost uk 80 100, 200, UrS and RS2 range from 1985 MC to the 1997 UrS AAN and 1995 RS2 ADU, so the best parts could be found in wrecking yards.