How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located at the top of the transmission, above the flywheel ring gear. It sends a signal to the ECU via a grey wire (T55/49), then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
Located on the edge of the transmission above the flywheel ring gear G28 Engine Speed Sensor sends a signal to ECU pin T55/49 using a grey wire. The ECU then utilizes this information to regulate the flow of fuel, timig and boost. It also sends a signal to the G5 tachometer inside the instrument cluster.
The sensor is used to correlate with the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and the location of the camshaft so it can activate spark and injectors according to the situation.
If this sensor fails to function, 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 a chain stretch or a jump in the chain link of the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
Testing is a bit tricky since there are two connector pins, and they have different functions but the best method of testing it is to measure resistance between the sensor and the ECU. If the sensor is functional, it should read approximately 1000 ohms. If you are having problems with this part, check for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, as i was accelerating off the highway paytoll at maximum speed I noticed a massive drop in power. It was as if the engine had run out of gas. Or my injectors were not firing. In the morning, i removed the spark plugs, three were drenched in gazoline, the 4th one was dry. When I start the engine without sparks, I put a piece of tissue on the top of each of the injector holes and the 3 that were drenched in gazoline leap out, however the 4th stays closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. Therefore, i think the issue is elsewhere.
I also tried to reset the PID but with no luck. The car will start when the G28 is unplugged, and it runs fine with the G28 plugged in. However, the intermittent misfire problem still occurs at higher RPM. The coolant sensor (G62), even when it is unplugged, shows a temperature of -49c. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I don't know what to do. I believe that I've ruled everything else out. But i am afraid I might have missed something. If anyone has suggestions, please let me know! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal by the RPM sensor. The GM-style transmitter is identical to the G4 and both are used in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or in a local parts store. Test them out by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black connector's end). They must be infinite Ohms.
4. check here ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to know the speed and position of the crankshaft to make decisions about fuel injector timing etc. It uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If either of these sensors go bad you will get codes on the diagnostic scanner which can cause the engine to shut down.
A failing G28 sensor could result in an inaccurate speed counter for your gearbox, here a gearbox that shifts faster than normal, or a misfire in gear. It is probable that the sensor is failing and needs to be replaced if you experience any of these symptoms. They are cheap and easy-to-find particularly audi advanced key when they're a Bosch sensor like ours. Alternately, GM's version this part is an excellent choice.
5. Tachometer
A malfunctioning engine sensor can cause a variety of issues in your vehicle. It is a crucial part of your Audi's transmission, since it relays information to the ECU about how fast or slow the vehicle's crankshaft is turning. If this sensor fails, it can affect the performance of the transmission and the rest audi replacement keys of the car's components.
The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It sends a signal via a gray wire to the ECU pin T55/49. The ECU then uses and processes this signal to control the flow of fuel, timig and boost and then transmitting it to the G5 tachometer inside the instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between pin T6a/1 and the instrument cluster pin T26a/12. You should see an average resistance of 1000 ohms in these areas. This is the same website across the Audi 80-100-200-RS2 range, from the 1985 MC all the way up to the 1997 UrS An and 1995 RS2 Du, so you might find them in wrecking yards.