How to Replace an Audi G28 Engine Speed Sensor
In this video Charles the Humble Mechanic demonstrates how to replace the G28 engine speed sensor. This sensor is located near the edges of the transmission, above the flywheel ring gear. It sends a message to the ECU through an uncolored wire T55/49, then to the tachometer on the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear G28 Engine Speed Sensor sends signals to ECU pin T55/49 using the grey wire. The ECU utilizes this information to control boost and fuel. It also sends signals to the G5 tachometer in the instrument cluster.
The sensor is used to link the G40 Camshaft position Sensor. The ecu has to know when the crankshaft has reached TDC, and the location of the camshaft so that it can activate the spark and injectors.
If this sensor fails the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are not in sync and could indicate the chain stretching or a jump link on the upper chain of timing. However the code will not appear on its own without additional information from other sensors (G4 and G40).
It is a little tricky to test since there are different connector pins, and they all have different functions. The best method for doing this is by measuring the resistance between the ECU and the sensor. When the sensor is functional, it should read approximately 1000 ohms. If you're experiencing issues with this part, check for signs of oil or coolant in the connector bay.
2. Injectors
Yesterday, when i was accelerating to the fullest speed from highway paytoll i had a big cut in power as if the engine was running out of gas or the injectors aren't firing at all. I pulled out the spark plugs this morning, three were drenched in gasoline and the fourth was unclean. I put a piece of tissue over each injector hole and when I turn the engine on without sparks, the three that have gazoline pop right out. The fourth one remains shut. I checked the ground connection on ECU pins 14/55/30/55/48/55/14/55/48/ i get zero ohm. I think the issue is somewhere else.
I also tried to reset the PID but with no luck. The car is able to start if 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 sensor (G62) even when unplugged, still shows an ice temperature of -49c. Also, i noticed that the oil pressure gauge in the cockpit is showing 2 bar, whereas the actual pressure is 0.0 when I crank up the engine.
I'm not certain what to do, as i think i've pretty much eliminated everything else. I'm worried that i might have missed something. Please let me know if you have any ideas! TIA!
3. Fuel Pump
The fuel pump in the g28 is activated by a signal sent from 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 parts store. Test them out to do - just put your DMM more info in resistance mode website and measure between pins 1 (with the bump on the connector end up) and 2 (2nd from left on the black connector's end). They must be infinite ohms.
4. ECU
Our 20vt turbo (3B AAN, ABY and ADU) engines are equipped with an ECU that needs to be aware of the speed and position of the crankshaft in order to make decisions about fuel injector timing etc. To accomplish this, it uses 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 show codes that could lead to the engine shutting down.
A malfunctioning read more G28 sensor could result in an inaccurate gearbox speed counter, a gearbox that shifts more quickly than normal, or an unfire when in the gear. It is probable that the sensor is failing and needs to be replaced if you notice any of these symptoms. The good news is that they are quite website affordable and easy to find, especially in the case of the Bosch unit like ours. Alternately, GM's version this part would be an option.
5. Tachometer
A failing engine speed sensor could be the cause of many issues in your vehicle. It is an important part of the transmission of your Audi since it sends more info information to the ECU regarding how fast or slow the engine is turning. If this sensor fails, it can cause problems for the transmission, as well as the other car's components.
The G5 engine speed sensor is situated on the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via an uncolored wire. The ECU utilizes this signal to regulate fuel and boost, as well as timig. It also relays it to the G5 Tachometer inside the instrument cluster. You can check 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 [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be a resistance of approximately 1000 ohms in these areas. This part is common across the Audi 80-100-200-RS2 range, from the 1985 MC up to the 1997 UrS AN and the 1995 RS2 Du You may also find some good ones in wrecking yards.