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In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located at the edge of transmission, above the flywheel gear. It transmits a signal to the ECU through the grey wire T55/49 and then to the tachometer on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU then uses this information to control the boost, fuel, and timig. It also sends signals to the G5 tachometer in the instrument cluster.

The sensor is used as a reference for comparing 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, in order to activate the spark and injectors.

If this sensor fails, the ECU will display a P00160 error code. This means that the Crank Shaft is out of alignment with the Intake Camshaft. It could also be a sign of the possibility of a chain stretch or jumpy chain link in the upper chain. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).

It's a bit tricky to test since there are different pins on the connector and each one has different functions. The most effective method to test it is to measure the resistance between the ECU and the sensor. When the sensor is operational, it should read approximately 1000 ohms. Examine for signs of coolant, or oil in the connector bay if you are experiencing issues with this part.

2. Injectors

Yesterday, while accelerating from the highway paytoll at maximum speed I noticed a significant decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. Today, i pulled out the spark plugs, 3 were drenched in gazoline, the fourth one was dry. When I start the engine without sparks, I put a piece of tissue on top of each injector hole and the 3 drenched with gazoline pop out, but the 4th stays shut. I tested the ground connection on ECU pins 14/55, 30/55 and 48/55. i get 0ohm. I think the issue is elsewhere.

I also tried to reset the PID but with no luck. The car is able to start if the G28 is unplugged and is running fine when it is plugged in however it is experiencing intermittent misfires at higher RPM. The coolant sensor (G62), even when it is unplugged, shows temperatures of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars when the actual pressure is zero.

I'm not sure what to do, as i think i've pretty much completely ruled out all other possibilities. I'm afraid i may have missed something. If anyone has suggestions, please chime in! TIA!

3. Fuel Pump


The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter functions similarly to the G4 sender and works on the 80,100,200, UrS, and RS2 vehicles. You can easily find a spare in a wrecking shop or a parts store. Test them out to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from the left on the black connector's end). They must be infinite Ohms.

4. ECU

The ECU in our 20vt turbo (3B AAN ABY ADU) engines needs to know both the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, etc. To accomplish this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If you have a problem with either one of these, the diagnostic scanner will display the codes that could trigger an engine shutdown.

A malfunctioning G28 sensor could cause an inaccurate speed counter for the gearbox, a gearbox that shifts faster than normal, and/or an unfire when in the gear. If you have any of these issues it is likely your sensor is going bad and needs replacing. They're inexpensive and easy to locate particularly when they're an Bosch model like ours. Alternately, GM's version this part is an excellent choice.

5. Tachometer

A malfunctioning engine speed sensor could be a cause for a slew of problems in your car. It is an important part of the transmission in your Audi because it relays information to the ECU regarding how fast or slowly the car's engine is spinning. If this sensor fails, it can disrupt the performance of the transmission and the rest of the car's components.

The G5 engine speed sensor is located on the edge of the transmission just above the flywheel ring gear. It transmits a signal to the ECU at pin T55/49 via a grey wire. The ECU uses this signal to regulate fuel and boost, and also timig. It also relays it to the G5 Tachometer in instrument cluster. You can check 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 [79]), and between pin T6a/1 as well as pin T26a/12. You should observe around 1000 ohms of resistance between those two pins. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS An and 1995 RS2 Du You may also find good ones in wrecking yards.

Read More: https://www.g28carkeys.co.uk/audi-car-key-replacements-near-me/